ASE T-series practice test: 53 questions

Incorrect: A failed crank position sensor upsets timing for every cylinder or stops the engine, not just one coil pair.

Incorrect: An intake gasket leak leans out the cylinders next to it; it would not line up exactly with the two cylinders that share one coil.

Incorrect: A restricted fuel filter starves all cylinders together, mostly under load.

Correct: On a waste-spark system one coil fires both cylinders of a pair, so a misfire limited to exactly that pair points at its coil.

Incorrect: A plugged catalytic converter causes power loss and high backpressure, not a cold-only tick.

Incorrect: A worn rod bearing knocks louder as the oil thins with heat and under load; it does not go away when warm.

Incorrect: A loose accessory belt squeals or chirps rather than ticking, and warming up does not cure it.

Correct: A cracked exhaust manifold ticks when cold because the crack is open, then the metal expands with heat and closes it, so the noise fades.

Incorrect: An exhaust leak ahead of the O2 sensor pulls in outside air, so it reads falsely lean, not rich.

Correct: A torn regulator diaphragm lets fuel get pulled into the intake through the vacuum hose, so the mixture runs rich; the high O2 voltage and −20% trim both show that.

Incorrect: An open O2 heater slows the sensor's warm-up and sets a heater code; on a warm engine it does not hold the reading rich.

Incorrect: A vacuum leak at the intake manifold adds unmetered air and makes the engine lean, so the sensor would read low and trim would go positive.

Incorrect: Preload set too tight holds the valve slightly open and costs compression; it does not make a tick that stops once oil pressure builds.

Correct: A lifter with a leaking check valve bleeds down overnight and ticks until oil pressure refills it, which matches the short tick at cold start; Technician A's tight preload would not tick.

Incorrect: Only the leaking check valve fits: tight preload holds a valve open rather than making a brief start-up tick.

Incorrect: Technician B describes the classic cause: a leaking check valve lets the lifter bleed down while parked, so it ticks until oil refills it.

Incorrect: A vent valve stuck open causes an EVAP leak code; it does not send extra vapor into the engine.

Incorrect: A restricted fill-pipe recirculation line causes slow filling and nozzle shutoff, not a rough start afterward.

Incorrect: A loose fuel cap sets an EVAP leak code but does not affect starting or idle.

Correct: A purge valve stuck open lets vapor from the full, freshly filled tank pour into the intake, so the engine floods and runs rough just after refueling.

Incorrect: Normal sensor operation is fast, full switching between rich and lean, not one narrow cycle every 3 seconds.

Incorrect: High fuel pressure makes the sensor stay high, above about 0.45 V, rather than drift slowly in the middle.

Incorrect: A vacuum leak drives the reading low and keeps it there; it does not create a slow mid-range swing.

Correct: A healthy heated zirconia sensor switches across about 0.1–0.9 V several times a second at 2,500 rpm; a slow, narrow swing like this is an aged or contaminated sensor.

Incorrect: Gear train whine comes from the timing gears and their lash, not from flywheel face runout.

Incorrect: Oil pressure depends on the pump, bearings and oil; flywheel face runout has no effect on it.

Correct: A flywheel face that runs out wobbles against the disc, so the clutch grabs unevenly and chatters as it engages.

Incorrect: Cam lobe wear comes from lubrication, valve spring or lifter problems, not from the flywheel face.

Incorrect: A restricted air cleaner limits power and causes smoke under load; it does not make the idle erratic, so Technician A is wrong.

Correct: A loose suction-side fitting lets air into the fuel, which upsets rail pressure and the idle; a restricted air cleaner shows up under load, not at idle.

Incorrect: Only Technician B's cause fits: a restricted air cleaner affects power at load, not idle quality.

Incorrect: Technician B is right: air drawn in at a loose suction fitting aerates the fuel and makes rail pressure and idle unstable.

Correct: In a HEUI injector, high-pressure engine oil pushes an intensifier piston that multiplies the pressure on the fuel; the IPR valve controls that oil pressure, not fuel supply pressure.

Incorrect: The IPR valve controls injection control pressure, which is engine oil, not fuel supply, so Technician B is wrong.

Incorrect: Only Technician A is right; the IPR valve regulates the high-pressure oil circuit, not the fuel supply.

Incorrect: Technician A is right: the intensifier piston multiplies oil pressure to create injection pressure.

Incorrect: Measuring at the oil hole in one direction misses both checks and puts the spindle over an edge.

Correct: Two readings 90° apart at the same spot show out-of-round, and comparing each end of the journal shows taper.

Incorrect: One reading at the center cannot show out-of-round or taper.

Incorrect: The fillet radius is not a bearing surface, and a micrometer cannot give a true reading on it.

Incorrect: DEF is used by the SCR system after the DPF; it plays no part in the DOC's exotherm.

Incorrect: A DPF pressure sensor affects soot readings and when regeneration starts; it does not stop the DOC from heating the exhaust.

Correct: Good doser flow and a DOC above light-off should give a strong temperature rise across the catalyst; no rise means the DOC face is plugged or the catalyst is poisoned.

Incorrect: Doser flow already tested good, so a plugged nozzle is ruled out.

Incorrect: A crack between the valve seats can send combustion pressure into a coolant passage, but a leaking injector sleeve can do the same, so Technician B is also right.

Incorrect: A leaking injector sleeve (cup) can let compression into the coolant, but so can a cracked head, so Technician A is right as well.

Correct: With the gasket ruled out, bubbles in the radiator point to another way into the coolant: a crack between the valve seats or a leaking injector sleeve.

Incorrect: Both are known causes: a cracked head between the seats and a leaking injector sleeve both put combustion gas into the coolant.

Correct: Recession beyond the limit means the seat has been cut too deep; a new seat insert (and valve if needed) brings the valve back to the correct height.

Incorrect: Grinding the stem tip shorter corrects installed stem height, not the valve face depth in the deck.

Incorrect: A spring shim restores spring installed height, not the valve depth below the deck.

Incorrect: A thicker head gasket changes the piston-to-head clearance and compression, not how deep the valve sits in the head.

Incorrect: Tube runout makes the shaft vibrate, but it does not wear out one U-joint bearing and leave rust dust.

Incorrect: Wrong yoke phasing causes a vibration, but it leaves no rust-colored powder at one bearing cap.

Incorrect: Loose center bearing bolts cause a shake or clunk at the center support, not powder at a U-joint cap.

Correct: Rust-colored powder at a bearing cap is dry, worn needle bearings grinding themselves to dust; the worn joint then lets the shaft wobble and vibrate.

Correct: A hot-shift PTO drives through a clutch pack, and low apply pressure lets that pack slip under load; gear backlash makes noise, not slip.

Incorrect: Too much backlash makes the PTO noisy, but gears cannot slip; slipping under load points to the clutch pack, so Technician B is wrong.

Incorrect: Only Technician A's cause fits; backlash affects gear noise, not clutch slip.

Incorrect: Technician A is right: low apply pressure lets the PTO clutch pack slip when the pump is loaded.

Incorrect: The output shaft seal is at the back of the transmission, so a leak there shows up at the driveshaft yoke, not in the flywheel housing.

Incorrect: A worn damper spring causes rattle or clutch noise; it is not a source of oil.

Correct: Gear oil in the flywheel housing with a dry rear main area comes from the front of the transmission, past the input shaft bearing cover seal.

Incorrect: A plugged range cylinder exhaust affects range shifting; it does not move gear oil into the bell housing.

Incorrect: Turning the yoke one spline puts the yokes out of phase and still leaves worn splines.

Incorrect: Grease cannot restore worn splines, and the play is already over the limit now.

Correct: Radial play of 0.012 in. against a 0.007 in. limit means the splines are worn, so the slip yoke and its mating splined shaft are replaced as a set.

Incorrect: The grease seal keeps dirt out and grease in; replacing it does nothing for worn splines.

Incorrect: Dividing by the diameter gives a number in the wrong units, not torque.

Correct: Torque equals force times the lever arm, and the cord pulls at the yoke's radius, so the scale reading times the radius gives rolling torque.

Incorrect: Using the diameter doubles the lever arm and doubles the result.

Incorrect: The yoke's weight acts straight down through the pinion center and adds no turning torque.

Correct: A low reservoir plus fluid at the bell housing means fluid is leaving the system at the slave cylinder, which is then inspected and replaced.

Incorrect: Bleeding treats the air but not the leak that lets fluid escape at the bell housing.

Incorrect: A worn disc does not cause a soft pedal or fluid loss, so pulling the transmission for it would not fix this.

Incorrect: Master cylinder bypass happens inside the cylinder, so it does not lower the reservoir or put fluid at the bell housing.

Incorrect: Purging at each cut-out is exactly how the dryer is meant to work, so it cannot be the cause.

Incorrect: A cut-out between 120 and 135 psi is a normal range and does not put water in the tanks.

Correct: Oil from a worn compressor coats the desiccant so it can no longer absorb water; the dryer still purges, but wet air gets through.

Incorrect: Cooling the air before the dryer lets moisture condense and drop out, which is the intended design.

Correct: When stroke is excessive, the S-cam rotates so far that the rollers go past the lobe's high point and hold the shoes out; out-of-adjustment brakes are the usual cause.

Incorrect: A weak return spring slows release, but it does not let the cam roll over center.

Incorrect: The lining's friction rating changes braking feel, not how far the cam rotates.

Incorrect: A restricted quick release exhaust slows release, but it does not move the cam past its lobe.

Incorrect: An open modulator solenoid sets a fault and stops ABS from working at that wheel; it does not trigger ABS.

Incorrect: Worn linings reduce braking at that wheel; they would not make the wheel look locked to the ABS.

Correct: A sensor pushed back from the tone ring gives a weak or broken signal at low speed, so the controller sees false wheel lockup and cycles ABS on gentle stops.

Incorrect: A leaking relay valve affects both rear brakes and leaks air; it does not create a false lockup signal at one wheel.

Incorrect: A DOT marking and date code are required markings, not a defect.

Incorrect: Being routed through its retaining clips is the correct installation.

Correct: A hose that bulges under pedal pressure has a weak inner layer, which wastes pedal travel and can burst, so it must be replaced.

Incorrect: Fine surface checking on the cover is minor aging; cracks deep enough to show the reinforcement would be a reason to replace.

Incorrect: Banjo fittings seal on their washers, not on the threads, so thread sealant will not stop the leak and can contaminate the system; Technician A is wrong.

Correct: A banjo fitting seals on its two crush washers, so new washers and the specified torque fix the leak; thread sealant does nothing there.

Incorrect: Only Technician B is right; sealant on banjo bolt threads does not reach the sealing faces.

Incorrect: Technician B is right: new sealing washers and the correct torque seal a banjo fitting.

Incorrect: If both the dash gauges and a master gauge show 110–125 psi, pressure is not falling to the warning point, so a leak is not the cause; Technician A is wrong.

Incorrect: A governor that cuts in early would keep pressure higher, not trigger a low-air warning, so Technician B is wrong.

Incorrect: Neither explanation fits when every gauge shows normal pressure.

Correct: Pressure stays at 110–125 psi, so the buzzer is false; the low-pressure switch or its wiring is the likely fault, not a leak or the governor.

Correct: Square port bosses and a stroke tag are how long-stroke chambers are marked, and a long-stroke Type 24 has a higher adjustment limit, so Technician B is wrong.

Incorrect: A long-stroke Type 24 has a longer adjustment limit (2 in), so not every Type 24 uses 1-3/4 in; Technician B is wrong.

Incorrect: Only Technician A is right; a long-stroke Type 24 has a higher limit than the standard 1-3/4 in.

Incorrect: Technician A is right: square port bosses and a rated-stroke tag mark a long-stroke chamber.

Incorrect: The cross tube sets toe, not camber.

Correct: Camber on a solid I-beam axle is not adjustable, so camber out of spec on both sides means the beam or knuckles are bent and are replaced per the manufacturer.

Incorrect: Eccentric camber bolts are found on independent suspensions, not on a solid I-beam axle.

Incorrect: There are no camber shims at the kingpin bosses of an I-beam axle.

Incorrect: Setting toe first is wasted work, because setting caster afterward changes it.

Incorrect: Camber on an I-beam axle is not set with shims, and toe is always the last adjustment.

Incorrect: Toe set before caster will be thrown off when caster is adjusted.

Correct: On an I-beam axle, camber is checked (it is not adjustable), caster is then set, and toe is set last because changing caster can change it.

Incorrect: A worn or loose fifth wheel lock lets the kingpin move in the jaws, but a kingpin worn below its gauge limit allows the same slack, so Technician B is right too.

Incorrect: A worn kingpin allows slack in the jaws, but so does a worn or misadjusted lock, so Technician A is right as well.

Correct: A clunk on starts and stops is slack between kingpin and jaws; a worn or misadjusted lock and a kingpin worn below gauge both create it.

Incorrect: Both are classic causes of fifth wheel slack: the lock and the kingpin.

Incorrect: Shock absorbers damp vertical motion and do not locate the axle side to side, so worn shock bushings would not let it shift sideways; Technician A is wrong.

Correct: The transverse torque rod (track bar) holds the axle centered under the frame; worn bushings let it shift sideways over bumps until the tires rub.

Incorrect: Only Technician B is right; shock bushings do not control the axle's sideways position.

Incorrect: Technician B is right: worn track bar bushings let the axle move sideways.

Incorrect: The bead seat area is used for radial runout of the bare wheel, not side-to-side wobble.

Correct: Lateral runout is side-to-side wobble, so the dial indicator rides on the side of the rim flange while the wheel turns.

Incorrect: The tread center is where radial (up-and-down) runout of the tire is read, not lateral runout.

Incorrect: Rocking the wheel at the valve stem checks for bearing play, not runout.

Correct: A glazed belt slips even at the correct tension, so it is replaced and the pulleys are checked for glazing, wear and alignment.

Incorrect: Belt dressing is a temporary fix that makes residue and does not cure a glazed belt.

Incorrect: Overtightening wears out the bearings and still does not stop a glazed belt from slipping.

Incorrect: The pump has not been tested; the glazed belt explains the low assist at idle.

Incorrect: A worn upper column bearing makes noise or play at the steering wheel, not housing movement.

Incorrect: Worn inner tie-rod sockets give play at the tie rod, but they do not make the rack housing move on its mounts.

Correct: If the rack housing visibly moves on its mounts, the mounting bushings are worn, which lets it clunk as the wheel is turned.

Incorrect: Low pump flow makes steering heavy, not a clunk with the housing moving.

Correct: The park switch keeps the wiper motor running after the switch is turned off until the blades reach park; an open in that circuit stops them wherever they are.

Incorrect: High ground resistance makes the wipers run slowly, not stop out of park.

Incorrect: A worn or disconnected linkage would leave the motor running but the blades not moving.

Incorrect: A shorted speed switch causes wrong speeds or wipers that will not shut off, not blades that stop in place.

Incorrect: A brushless alternator has no brushes to wear, so Technician A is wrong.

Correct: With no brushes to wear out, the regulator and field circuit are tested by the maker's procedure; Technician A is wrong because a brushless alternator has no brushes.

Incorrect: Only Technician B is right; there are no brushes in a brushless alternator.

Incorrect: Technician B is right: testing the regulator and field circuit per the manufacturer is the correct approach.

Incorrect: An open fuse would leave no voltage at the feed terminal, but 12.4 V is there.

Incorrect: The backup lamps work and the alarm feed has 12.4 V, so the reverse switch is working.

Correct: Full voltage at the feed and a good ground (0.1 V) mean the alarm is getting what it needs, so the alarm itself has failed.

Incorrect: Only 0.1 V on the ground terminal shows a good ground.

Correct: If the motor runs when powered and grounded directly, it is good, so the fault is in the switch or its wiring.

Incorrect: The motor ran normally on jumper leads, which shows it is working, so Technician B is wrong.

Incorrect: Only Technician A is right; the direct-power test cleared the motor.

Incorrect: Technician A is right: with the motor proven good, the switch or its wiring is the suspect.

Incorrect: A faulty cruise switch would affect cruise only, not the horn and airbag circuits.

Incorrect: A crash sensor fault would set the airbag lamp, but it would not take out the horn and cruise switches.

Incorrect: A blown horn fuse would kill the horn only, not the cruise switches or the airbag circuit.

Correct: The clock spring carries the airbag, horn and switch circuits from the column to the turning wheel, so if it opens, all three fail together.

Incorrect: A bad battery ground affects supply voltage to everything, but it would not put 12 ohms between CAN high and ground.

Correct: A healthy CAN wire is not connected to chassis ground, so 12 ohms to ground means insulation has worn through and the wire touches the frame.

Incorrect: An open CAN low wire shows as high or infinite resistance in that wire, not a low reading from CAN high to ground.

Incorrect: A failed terminating resistor changes the reading between CAN high and CAN low, not between CAN high and ground.

Incorrect: 1.00 V comes from subtracting only the load voltage and ignoring the 0.15 V lost on the supply side.

Incorrect: The 0.85 V figure is right, but a drop that large means the ground path has high resistance, so it is not acceptable.

Incorrect: 0.15 V is the supply-side drop, not the ground-side drop.

Correct: Ground drop is total minus supply drop minus load voltage: 12.60 − 0.15 − 11.60 = 0.85 V, far more than a ground path should lose.

Correct: A thermostat stuck open makes the engine run cool, especially in cold weather; it cannot make it overheat on a grade.

Incorrect: A fan clutch that does not engage leaves the radiator without forced air when it is needed most.

Incorrect: Plugged radiator tubes reduce coolant flow and cooling, which shows up under full load.

Incorrect: A missing or damaged shroud lets the fan pull air around the radiator instead of through it.

Correct: A system that loses vacuum after the pump is isolated has a leak; Technician B is wrong because holding vacuum does not prove the moisture is gone.

Incorrect: A short vacuum hold only shows the system is tight; moisture is removed by a long enough evacuation to a deep vacuum, so Technician B is wrong.

Incorrect: Only Technician A is right; a vacuum hold proves tightness, not dryness.

Incorrect: Technician A is right: a system that will not hold vacuum after isolation has a leak.

Incorrect: The expansion valve or orifice tube meters refrigerant into the evaporator.

Incorrect: The pressure drop from high-pressure liquid to low-pressure mixture happens at the expansion device.

Correct: The receiver-drier stores liquid refrigerant, filters out debris and holds desiccant that absorbs moisture.

Incorrect: Compressing refrigerant is the compressor's job.

Incorrect: Plugging in an actuator with the key on can make it calibrate to a wrong position; it is connected with the key off, then calibrated as the maker specifies.

Incorrect: Many replacement actuators must be calibrated, by a key cycle or a scan tool, so Technician B is wrong.

Incorrect: Both statements are wrong: the actuator is plugged in with the key off, and most replacement actuators need calibration.

Correct: A new actuator is connected with the key off and then calibrated as the manufacturer specifies, so neither statement is correct.

Incorrect: Zero resistance would mean a shorted sensor, not a cold one.

Incorrect: A thermistor's resistance changes with temperature; staying the same means it is bad.

Correct: An NTC (negative temperature coefficient) thermistor's resistance goes up as temperature goes down, so in ice water it rises.

Incorrect: Decreasing resistance in the cold is how a PTC sensor behaves, not an NTC.

Incorrect: 2.4 gallons is the extra glycol needed (6 − 3.6), but each gallon drained also removes some glycol, so more must be drained.

Correct: Drain x and add pure glycol: 0.30 × (12 − x) + x = 6, so 0.7x = 2.4 and x ≈ 3.4 gallons.

Incorrect: 4.8 gallons overshoots and would push the mix well above 50%.

Incorrect: 6.0 gallons is half the system, which would give about 65% glycol.

Incorrect: Frayed webbing is a defect even if the buckle works, because the belt can tear in a crash; Technician A is wrong.

Correct: Belt anchors, tethers and sleeper restraints must be securely mounted, and frayed webbing is a defect whatever the buckle does.

Incorrect: Only Technician B is right; frayed webbing must be repaired even when the buckle latches.

Incorrect: Technician B is right: anchors, tethers and sleeper restraints are checked for secure mounting during a PMI.

Incorrect: Checking U-joints with the engine running and the transmission in gear is unsafe; it is done with the engine off and the wheels chocked, so Technician A is wrong.

Incorrect: Slip-yoke splines need grease so they can slide freely, so Technician B is wrong.

Incorrect: Both statements are wrong: the check is made with the engine off, and the splines need grease.

Correct: U-joints are checked by hand with the engine off and the wheels chocked, and slip-yoke splines are greased at service, so neither statement is right.

Incorrect: 55 psi is the in-service limit in 49 CFR 393.51 (or half of governor cut-out), not the FMVSS 121 figure for new vehicles.

Incorrect: 70 psi is above the warning point the standard sets.

Incorrect: 45 psi is too low and is in the range where spring brakes begin to apply.

Correct: FMVSS 121 requires the low-air warning on a new vehicle to come on by the time service reservoir pressure drops to 60 psi.

Correct: A level at MIN that sets the warning on grades and braking means the coolant is low, so it is topped up and the system pressure tested to find the loss.

Incorrect: Bypassing a working sensor hides a real coolant loss.

Incorrect: 100% antifreeze gives poorer freeze protection and cooling than a 50/50 mix, and it does not find the leak.

Incorrect: The sensor is working correctly; it is reporting coolant that really is low.

Incorrect: Overinflation affects tread wear, not the wheel's clamping.

Correct: Rust streaks from the stud holes come from the wheel moving against the hub, which happens when the nuts are loose.

Incorrect: Normal paint wear does not form rust streaks radiating from stud holes.

Incorrect: Bearing end play affects hub movement, but it does not cause rust streaks at the stud holes.

Correct: AGM batteries are damaged by overcharging, so they are charged on a charger mode that limits voltage for AGM.

Incorrect: AGM batteries are sealed and cannot have water added.

Incorrect: AGM batteries are sealed, with no cells to check.

Incorrect: Fast charging at a high rate overheats an AGM battery and dries out its electrolyte.

Correct: An indicator outside its marked range means the belt has stretched or the wrong length was fitted, so the tensioner can no longer hold tension and the belt is replaced.

Incorrect: Automatic tensioners have no manual spring adjustment.

Incorrect: Spring force in an automatic tensioner is fixed, so the reading does not mean it is set too tight.

Incorrect: An out-of-range reading is a defect, not wear that can be ignored.