Ten ASE A1 Engine Repair questions in the ASE format: four options, one best answer. They are free to use, print and share, and there is nothing to sign up for on this page.
01How to use these
The questions come from the ToolboxPrep A1 bank and are spread across the test's content areas in the proportion the ASE test specification gives them: A (General Engine Diagnosis), B (Cylinder Head and Valve Train Diagnosis and Repair), C (Engine Block Diagnosis and Repair), D (Lubrication and Cooling Systems Diagnosis and Repair), E (Fuel, Electrical, Ignition, Air Induction and Exhaust Systems Diagnosis and Service). Answer each one before opening the explanation. Every explanation covers all four options, because knowing why the wrong answers are wrong is most of the skill.
- Pace. The A1 test gives you 75 minutes for 55 questions (45 scored, 10 unscored), about 1 min 22 s a question. Try these at that pace.
- Print. The printed version shows the questions and the answer key without the explanations, so it works as a handout.
02The questions
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The service information for a vehicle warns technicians to keep hands clear of the electric radiator fan, or to unplug it, when working near it on a hot engine, even after the ignition is switched off. Why?
- The fan module holds a charge that can shock
- The fan motor stays hot enough to burn skin
- The fan can start with the ignition off
- The fan runs whenever the A/C is charged
Show the answer
C. Correct. On vehicles like this one the fan control can run the fan after shutdown to pull heat out of a hot engine, so it can start without warning while hands are near the blades. Unplugging the fan removes that chance during the work.
Why not the others
A. A 12-volt fan circuit does not store a charge large enough to shock a technician. The warning exists because the fan can start by itself after the ignition is off.
B. A warm motor is not what the warning is about, and unplugging the fan would not cool it. The hazard is the fan starting on its own after shutdown, which unplugging prevents.
D. A charged A/C system does not run the fan by itself, and with the ignition off the A/C is off. The fan can start after shutdown because its control cools a hot engine, which is why the warning is given.
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The manufacturer specifies SAE 5W-30 for an engine, but at its last oil change it was filled with SAE 0W-16. Since then it has started using oil between changes. How can the oil grade cause this?
- Thin oil lowers the PCV valve's flow rate
- Thin oil raises the crankcase pressure
- Thin oil drains back to the pan too slowly
- Thin oil slips past the rings and guides
Show the answer
D. Correct. Oil much thinner than specified flows more easily through the small clearances at the oil control rings and the valve guides, so more of it reaches the combustion chambers and burns. Refilling with the specified grade comes before any judgment of the engine's oil consumption.
Why not the others
A. PCV flow is set by manifold vacuum and the valve's design, not by the oil grade in the pan. The thin oil is used up because it slips past the oil control rings and valve guides.
B. Crankcase pressure comes from blowby past the compression rings and how well the ventilation system removes it, not from the oil's grade. The thin oil is used up because it passes the rings and guides more easily.
C. Thinner oil drains back to the pan faster, not slower. It is used up because it flows more easily past the oil control rings and valve guides into the cylinders.
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A turbocharged pickup pings under hard acceleration, and the scan tool shows heavy knock retard. A vacuum/boost gauge teed into the intake manifold reads 20 in.Hg of vacuum at warm idle and 17 psi of boost at full load; the manufacturer specifies a maximum of 12 psi of boost. What do these readings show?
- Underboost from a restricted air filter element
- Normal boost for a full-load acceleration
- Overboost from a wastegate that is not opening
- Overboost from a compressor bypass valve stuck shut
Show the answer
C. Correct. Boost 5 psi over the 12 psi maximum (17 - 12 = 5) means exhaust is not being bypassed around the turbine, so the turbocharger keeps speeding up; a wastegate stuck shut, or a fault in what opens it (its actuator, hose or control solenoid), would do it. The extra cylinder pressure causes the pinging that the knock retard is fighting.
Why not the others
A. A restricted air filter starves the compressor and can only lower boost, but the gauge shows 17 psi, 5 psi above the 12 psi maximum. That is overboost, not underboost.
B. The manufacturer's maximum is 12 psi, and 17 psi is 5 psi over it. The pinging and knock retard come from that excess cylinder pressure.
D. The compressor bypass valve vents boost back to the compressor inlet when the throttle snaps shut; stuck shut it causes compressor surge on lift-off, and leaking it lowers boost. Peak boost is capped by the wastegate, so boost above the maximum points to a wastegate that is not opening.
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A cylinder leakage test on a warm six-cylinder engine reads 6, 8, 7, 24, 9 and 7 percent for cylinders 1 through 6. The manufacturer allows a maximum of 15 percent on any cylinder. What should the technician do next?
- Pass the engine on its 10 percent average
- Replace the head gasket next to cylinder 4
- Listen for where cylinder 4's air escapes
- Retest cylinder 4 at a higher regulator setting
Show the answer
C. Correct. Cylinder 4's 24 percent exceeds the 15 percent limit, so the next step is to find where its air goes: listen at the oil filler opening, the throttle body and the tailpipe, and watch the coolant at the radiator. Where the air comes out shows which part is leaking before anything is taken apart.
Why not the others
A. The limit applies to each cylinder, not the average. The six readings total 61 percent, an average of about 10.2 percent, which hides cylinder 4's 24 percent, over the 15 percent limit.
B. Cylinder 4 is out of limits, but a high reading alone does not say where the air leaks. Listening at the oil filler, intake, tailpipe and radiator locates the leak before any part is replaced.
D. The percent scale is valid only at the tester's calibration pressure, so a higher setting gives a meaningless number. Cylinder 4 already fails; locate where its air escapes.
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A technician is cleaning a cast aluminum cylinder head after removal. Technician A says it can go in the hot tank of caustic solution the shop uses for cast iron parts. Technician B says abrasive discs on a power tool can cut the soft deck out of flat and leave grit that gets into the oil. Who is right?
- A only
- B only
- Both A and B
- Neither A nor B
Show the answer
B. Correct. Technician B is right: power abrasive discs can remove soft aluminum unevenly and leave abrasive grit in passages, where it can reach the bearings. Technician A is wrong: the caustic solution used for cast iron attacks aluminum, so an aluminum head is cleaned with a chemical safe for aluminum.
Why not the others
A. Only Technician B is right. Technician A is wrong because caustic (sodium hydroxide) solution attacks and eats away aluminum; aluminum parts are cleaned with a cleaner made for aluminum. Technician B is right that abrasive discs can remove deck metal and leave grit behind.
C. Only Technician B is right. Abrasive discs can cut the deck out of flat and shed grit, as B says, but Technician A is wrong because caustic hot-tank solution for cast iron attacks aluminum.
D. Technician B is right: abrasive discs can remove aluminum unevenly and leave grit in the engine. Technician A is the one who is wrong, because caustic solution made for cast iron attacks an aluminum head.
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A technician is checking main bearing oil clearance with plastic gauging strip during engine reassembly. Which of these is the correct way to use the strip?
- Torque the cap to specification, leave the crankshaft still, then compare the strip's width with the scale
- Torque the cap to specification, turn the crankshaft one turn, then compare the strip's width with the scale
- Snug the cap by hand, leave the crankshaft still, then compare the strip's width with the scale
- Lay the strip over the oil hole, torque the cap to specification, then compare the strip's width with the scale
Show the answer
A. Correct. Torquing the cap to specification crushes the bearing to its installed shape, and the strip flattens to the exact gap between journal and bearing. Turning the crankshaft would smear it, so the cap is removed and the flattened width is read against the scale on the strip's envelope: the wider the strip, the tighter the clearance.
Why not the others
B. Turning the crankshaft with the strip in place smears and tears it, so its width no longer shows the gap. The cap is torqued and removed without moving the crankshaft, and the flattened width is then read against the scale.
C. A hand-snug cap does not crush the bearing shells into their installed shape, so the strip reads a gap larger than the real running clearance. The cap must be torqued to the manufacturer's specification before the strip is read.
D. Over the oil hole the strip has nothing beneath it to crush against, so part of it is pressed into the hole and its width there no longer shows the gap. The strip is laid across the journal clear of the oil hole, the cap is torqued without turning the crankshaft, and the width is read against the scale.
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The oil pressure warning lamp on an engine stays lit whenever the engine runs. A mechanical gauge connected at the oil pressure sender port reads 18 psi at hot idle and 52 psi at 2,500 rpm; the manufacturer specifies at least 7 psi at idle and 35 psi at 2,500 rpm. Which of these could be the cause?
- A failed oil pressure switch
- A worn oil pump rotor set
- Worn crankshaft main bearings
- Oil thinned by fuel dilution
Show the answer
A. Correct. The mechanical gauge shows pressure above the minimum at both speeds, so the engine is getting oil and the fault is in the warning circuit. A switch whose contacts no longer open under pressure keeps the lamp grounded; the switch is replaced and the lamp checked again (a short to ground in its wire would act the same way).
Why not the others
B. A worn pump moves less oil than the bearings leak off, so the mechanical gauge would read low, especially at hot idle. Here it reads 18 psi and 52 psi, both above the minimums, which rules out a supply problem.
C. Excess bearing clearance bleeds pressure out of the galleries and would pull the gauge reading below specification. A reading of 18 psi at idle against a 7 psi minimum shows the bearings are holding pressure.
D. Fuel dilution thins the oil and lowers pressure, which the mechanical gauge would show. With 18 psi at idle and 52 psi at 2,500 rpm the oil is holding normal pressure, so the lamp fault is electrical.
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Each morning an engine's radiator is about 1 qt low while the coolant reservoir is at or above its hot-full mark. The system passes a pressure test with no leaks, and the hose from the filler neck to the reservoir is new and tight. Which of these could be the cause?
- A thermostat stuck closed
- A cap pressure valve stuck open
- A cap vacuum valve stuck closed
- A heater core with a pinhole leak
Show the answer
C. Correct. Hot coolant expands past the pressure valve into the reservoir; as it cools, a vacuum forms in the radiator and the vacuum valve should open to draw it back. Stuck closed, it leaves the coolant in the reservoir and the radiator low (the hoses may even collapse when cold), so the cap is replaced.
Why not the others
A. A thermostat stuck closed makes the engine overheat with a cool radiator; it does not move coolant into the reservoir and leave it there overnight.
B. A pressure valve stuck open lets coolant flow to the reservoir at low pressure, but with nothing sealing the neck it also flows back as the engine cools, so the radiator would refill. It lowers the boiling point instead.
D. A leaking heater core loses coolant from the system, so the reservoir would not stay full while the radiator drops, and the pressure test would show a loss. Coolant stranded in the reservoir points to the cap's return valve.
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A port-injected four-cylinder has a cylinder 3 injector circuit DTC. Unplugged at 70°F, the injectors measure 12.2, 12.0, 1.8 and 12.3 ohms for cylinders 1 through 4; the manufacturer specifies 11.0 to 13.0 ohms. What do these readings indicate?
- Cylinder 3's injector winding is shorted
- Cylinder 3's injector winding is open
- Cylinder 3's injector nozzle is restricted
- The other three injectors read too high
Show the answer
A. Correct. A good winding reads 11.0 to 13.0 ohms, and 1.8 ohms means turns of the coil are shorted together. A shorted injector draws far more current than its circuit is built for, so the injector is replaced and the circuit rechecked before the DTC is cleared.
Why not the others
B. An open winding has no path for current and reads OL (infinite resistance) on the meter. A reading of 1.8 ohms is far below specification, which means the winding is shorted, not open.
C. A resistance check tests only the electrical winding; a restricted nozzle needs a balance or flow test to find. The 1.8-ohm reading shows a shorted winding.
D. Readings of 12.0 to 12.3 ohms sit inside the 11.0 to 13.0 ohm specification, so those three are good. Only cylinder 3, at 1.8 ohms, is out of range, and low.
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After a timing chain replacement, an engine cranks at normal speed but fails to start. While cranking, the scan tool shows 0 rpm, a spark tester shows no spark at any coil, and a noid light stays dark at every injector connector. Which of these could be the cause?
- A crankshaft position sensor unplugged
- A fuel pump relay left out of its socket
- A camshaft position sensor unplugged
- A blown fuse feeding the ignition coils
Show the answer
A. Correct. The PCM times both spark and injection from the crankshaft position (CKP) signal and reports engine speed from it, so with no CKP signal it shows 0 rpm and fires neither coils nor injectors. A connector disturbed near the timing cover is easy to miss after this job; plug it in and recheck before testing further.
Why not the others
B. Without the pump the engine gets no fuel, but the PCM would still see engine speed, fire the coils and pulse the injectors. Here all three are missing.
C. The scan tool's engine speed comes from the crankshaft position signal, so with only the camshaft sensor unplugged it would still show cranking rpm. Zero rpm with no spark and no injector pulses points to the crankshaft signal.
D. Losing the coil feed stops spark, and if that fuse also fed the injectors they would stop too, but the PCM would still see the crankshaft signal and the scan tool would still show cranking rpm. Here rpm reads 0, so the crankshaft signal itself is missing.
03Answer key
| Question | Answer | Content area |
|---|---|---|
| Q1 | C | General Engine Diagnosis |
| Q2 | D | General Engine Diagnosis |
| Q3 | C | General Engine Diagnosis |
| Q4 | C | General Engine Diagnosis |
| Q5 | B | Cylinder Head and Valve Train Diagnosis and Repair |
| Q6 | A | Engine Block Diagnosis and Repair |
| Q7 | A | Lubrication and Cooling Systems Diagnosis and Repair |
| Q8 | C | Lubrication and Cooling Systems Diagnosis and Repair |
| Q9 | A | Fuel, Electrical, Ignition, Air Induction and Exhaust Systems Diagnosis and Service |
| Q10 | A | Fuel, Electrical, Ignition, Air Induction and Exhaust Systems Diagnosis and Service |
04Questions by content area
Working on one part of the A1 test? Each content area has its own page with five more free questions.
05More free questions
The A1 study guide covers each content area and how to study for it, and the ASE A1 Engine Repair practice test page describes the full A1 question bank. The same free format is available for the other eight tests.
How these questions are written and checked: how our questions are made. Found a mistake? Tell us and we will fix it.
ToolboxPrep is an independent study site. It is not affiliated with or endorsed by ASE (the National Institute for Automotive Service Excellence). Our questions are original practice questions written to the published ASE test specifications; they are not actual test questions.