ASE A1 EXAAM SCRIPT 2025/2026 QUESTIONS WITH
SOLUTIONS MARKED A+
✔✔A noisy valve train is being diagnosed. Technician A says that the rocker arm may
be adjusted too tightly. Technician B says that the rocker arm may be adjusted too
loosely or may be worn. Which technician is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B - ✔✔The correct answer is b. Technician B is correct because noise
is created by the rocker arm pound- ing onto the end of the valve when the clearance
(lash) is greater than specified by the vehicle manu- facturer. Technician A is not correct
because the engine will not create noise if the valve clearance is too tight. The valves
may not close all the way if the clearance is too tight which could lead to a burned valve.
Answers c and d are not correct because only Technician B is correct.
✔✔Two technicians are diagnosing a problem with an OHV V-8 with flat-bottom lifters.
The valve covers have been removed and the engine is running. One pushrod is not
rotating. Technician A says that the camshaft is worn and must be replaced. Technician
B says that the lifter is worn and must be replaced. Which technician is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B - ✔✔The correct answer is c. Both technicians are correct.
Technician A is correct because it is the slight angle on the cam lobe that helps create a
rotating force on flat-bottomed lifters. If the lobe is worn, the lifter and the pushrod will
not rotate. Technician B is also correct because the bottom of a lifter is slightly convex
which helps rotate the lifter as it rides over the cam lobe. If the bottom of the lifter is
worn, it will not rotate. Answers a, b, and d are not correct because both technicians are
correct.
✔✔A head gasket failure is being diagnosed. Technician A says that an exhaust
analyzer can be used to check for HC when the tester probe is held above the radiator
coolant. Technician B says that a combustion tester liquid changes color in the
presence of combustion gases. Which technician is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B - ✔✔The correct answer is c. Both technicians are correct.
Technician A is correct because if exhaust gases are escaping from the combustion
chamber and into the coolant past a defective head gasket, HC (hydrocarbons) or CO
(carbon monoxide) emissions will be able to be measured above the coolant with the
,engine running. Technician B is correct because combustion tester liquid that changes
color when exposed to exhaust gases can also be used to verify a defective head
gasket. Answers a, b, and d are not correct because both technicians are correct.
✔✔Excessive exhaust system back pressure has been measured. Technician A says
that the catalytic converter may be clogged. Technician B says that the muffler may be
clogged. Which technician is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B - ✔✔The correct answer is c. Both technicians are correct.
Technician A is correct because a clogged catalytic converter can be the cause of an
exhaust system restriction. Technician B is correct because a clogged (or damaged)
muffler can cause an exhaust system restriction. A muf- fler can be clogged by parts
broken from the internal baffles. If the cat- alytic converter is replaced and the exhaust
is still restricted, a clogged muffler (or resonator) could be the cause. Answers a, b, and
d are not correct because both technicians are correct.
✔✔Technician A says that black exhaust smoke is an indication of a too-rich air-fuel
mixture. Technician B says that white smoke (steam) is an indication of coolant being
burned in the engine. Which technician is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B - ✔✔The correct answer is c. Both technicians are correct.
Whitesmoke or steam is an indication that coolant is getting into the combustion
chamber and is being va- porized by the heat of combustion. Technician A is correct
because an excessively rich air-fuel mixture will create black exhaust smoke. A slightly
rich engine may not emit black smoke because the cata- lytic converter will usually
oxidize the unburned fuel (hydrocarbons) into H2O (water) and CO2 (carbon dioxide).
Answers a, b, and d are not correct because both technicians are correct.
✔✔Technician A says that cranking vacuum should be the same as idle vacuum.
Technician B says that a sticking valve is indicated by a floating valve gauge needle
reading. Which technician is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B - ✔✔The correct answer is d. Neither technician is correct.
Technician A is not correct because the speci- fication for cranking vacuum is greater
than 2.5 in. Hg. Even though a sound engine with a completely closed throttle may be
able to produce 17 in. Hg to 21 in. Hg vacuum (at sea level) during cranking, it is not the
specification for cranking vacuum. Technician B is not correct because a floating
,vacuum gauge needle is an indication of an overly rich or lean air-fuel mixture, not a
sticking valve. A stick- ing valve will cause the vacuum gauge needle to move rapidly up
and down. Answer c is not correct because neither technician is correct.
✔✔Two technicians are discussing a cylinder power balance test. Technician A says
the more the engine RPM drops, the weaker the cylinder. Technician B says that all
cylinder RPM drops should be within 50 RPM of each other. Which technician is
correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B - ✔✔The correct answer is b. Technician B only is correct. All
cylinders should drop the same (within 50 RPM) when they are canceled or grounded
out. This indicates that each cylinder was contributing an equal amount of the operation
of the engine. If a cylinder drops the RPM less than others, the cylinder is weak.
Technician A is not correct because the more the engine RPM drops when a cylinder is
canceled, the more that cylinder is contributing to the operation of the engine. Answers
c and d are not correct because only Technician B is correct.
✔✔A cylinder leakage (leak-down) test indicates 30% leakage, and air is heard coming
out of the air inlet. Technician A says that this is a normal reading for a slightly worn
engine. Technician B says that one or more intake valves are defective. Which
technician is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B - ✔✔The correct answer is b. A leakage of 30% is excessive and if
air is heard escaping from the engine air inlet, then one or more intake valves must be
leaking. It is also possible that the cylinder being tested is not at TDC on the
compression stroke. If the cylinder were at TDC of the exhaust stroke, both intake and
exhaust valves would be open and air would also be heard coming from the tailpipe.
Technician A is not correct because 30% leakage is too much for a slightly worn engine.
Leakage should not exceed 20%. Answers c and d are not correct because only
Technician B is correct.
✔✔During a cylinder leakage (leak-down) test, air is noticed coming out of the oil fill
opening. Technician A says that the oil filter may be clogged. Technician B says that the
piston rings may be worn or defective. Which technician is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B - ✔✔The correct answer is b. Technician B is correct because if the
piston rings were worn (or broken), compressed air could escape past the rings and
, flow into the crankcase. The air would then escape from the engine through the oil
drain-back holes and other openings in the block and eventually be heard at the oil fill
opening. Technician A is not correct because the oil filter is not being tested and the
compressed air entering the combustion chamber could not get into or past the oil filter.
Answers c and d are not correct because only Technician B is correct.
✔✔The low oil pressure warning light usually comes on ______________.
a. whenever an oil change is required
b. whenever oil pressure drops dangerously low (3 to 7 psi)
c. whenever the oil filter bypass valve opens
d. whenever the oil filter anti-drain-back valve opens - ✔✔The correct answer is b. The
oil pressure light comes on whenever the pressure drops to between 3 and 7 psi.
Answer a is not correct because the oil pressure light is not the same as the amber
"change oil soon" light. Answer c is not correct because there is no indication when the
bypass valve opens, which often occurs when the oil is cold or the oil filter is dirty and
creates a restriction. Answer d is not correct because this valve simply keeps oil from
draining back into the oil pan after the engine stops running.
✔✔Two technicians are discussing a compression test. Technician A says that the
engine should be cranked over with the pressure gauge installed for "3 puffs."
Technician B says that the maximum dif- ference between the highest-reading cylinder
and the lowest-reading cylinder should be 20%. Which technician is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B - ✔✔The correct answer is b. Technician B is correct because the
maximum difference, as specified by most vehicle manufacturers, is 20%. If the highest
reading is 160 psi, then the lowest cylinder com- pression should be greater than 128
psi (160 × 20% = 32 psi. 160 psi - 32 psi = 128 psi). Technician A is not correct because
the engine should be cranked through at least four compression events or 4 to 5 "puffs"
(not 3 "puffs"). Answers c and d are not correct because only Technician B is correct.
✔✔A compression test gave the following results:cylinder #1 = 155, cylinder #2 = 140,
cylinder #3 = 110, cylinder #4 = 105. Technician A says that a defective (burned) valve
is the most likely cause. Technician B says that a leaking head gasket could be the
cause. Which technician is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B - ✔✔The correct answer is b. Technician B is correct because if the
head gasket were leaking between cylinder number 3 and 4, the compression on these
cylinders would be lower than normal. The defec- tive gasket would allow compression
to escape to the adjacent cylinders. Technician A is not correct because a burned valve
SOLUTIONS MARKED A+
✔✔A noisy valve train is being diagnosed. Technician A says that the rocker arm may
be adjusted too tightly. Technician B says that the rocker arm may be adjusted too
loosely or may be worn. Which technician is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B - ✔✔The correct answer is b. Technician B is correct because noise
is created by the rocker arm pound- ing onto the end of the valve when the clearance
(lash) is greater than specified by the vehicle manu- facturer. Technician A is not correct
because the engine will not create noise if the valve clearance is too tight. The valves
may not close all the way if the clearance is too tight which could lead to a burned valve.
Answers c and d are not correct because only Technician B is correct.
✔✔Two technicians are diagnosing a problem with an OHV V-8 with flat-bottom lifters.
The valve covers have been removed and the engine is running. One pushrod is not
rotating. Technician A says that the camshaft is worn and must be replaced. Technician
B says that the lifter is worn and must be replaced. Which technician is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B - ✔✔The correct answer is c. Both technicians are correct.
Technician A is correct because it is the slight angle on the cam lobe that helps create a
rotating force on flat-bottomed lifters. If the lobe is worn, the lifter and the pushrod will
not rotate. Technician B is also correct because the bottom of a lifter is slightly convex
which helps rotate the lifter as it rides over the cam lobe. If the bottom of the lifter is
worn, it will not rotate. Answers a, b, and d are not correct because both technicians are
correct.
✔✔A head gasket failure is being diagnosed. Technician A says that an exhaust
analyzer can be used to check for HC when the tester probe is held above the radiator
coolant. Technician B says that a combustion tester liquid changes color in the
presence of combustion gases. Which technician is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B - ✔✔The correct answer is c. Both technicians are correct.
Technician A is correct because if exhaust gases are escaping from the combustion
chamber and into the coolant past a defective head gasket, HC (hydrocarbons) or CO
(carbon monoxide) emissions will be able to be measured above the coolant with the
,engine running. Technician B is correct because combustion tester liquid that changes
color when exposed to exhaust gases can also be used to verify a defective head
gasket. Answers a, b, and d are not correct because both technicians are correct.
✔✔Excessive exhaust system back pressure has been measured. Technician A says
that the catalytic converter may be clogged. Technician B says that the muffler may be
clogged. Which technician is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B - ✔✔The correct answer is c. Both technicians are correct.
Technician A is correct because a clogged catalytic converter can be the cause of an
exhaust system restriction. Technician B is correct because a clogged (or damaged)
muffler can cause an exhaust system restriction. A muf- fler can be clogged by parts
broken from the internal baffles. If the cat- alytic converter is replaced and the exhaust
is still restricted, a clogged muffler (or resonator) could be the cause. Answers a, b, and
d are not correct because both technicians are correct.
✔✔Technician A says that black exhaust smoke is an indication of a too-rich air-fuel
mixture. Technician B says that white smoke (steam) is an indication of coolant being
burned in the engine. Which technician is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B - ✔✔The correct answer is c. Both technicians are correct.
Whitesmoke or steam is an indication that coolant is getting into the combustion
chamber and is being va- porized by the heat of combustion. Technician A is correct
because an excessively rich air-fuel mixture will create black exhaust smoke. A slightly
rich engine may not emit black smoke because the cata- lytic converter will usually
oxidize the unburned fuel (hydrocarbons) into H2O (water) and CO2 (carbon dioxide).
Answers a, b, and d are not correct because both technicians are correct.
✔✔Technician A says that cranking vacuum should be the same as idle vacuum.
Technician B says that a sticking valve is indicated by a floating valve gauge needle
reading. Which technician is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B - ✔✔The correct answer is d. Neither technician is correct.
Technician A is not correct because the speci- fication for cranking vacuum is greater
than 2.5 in. Hg. Even though a sound engine with a completely closed throttle may be
able to produce 17 in. Hg to 21 in. Hg vacuum (at sea level) during cranking, it is not the
specification for cranking vacuum. Technician B is not correct because a floating
,vacuum gauge needle is an indication of an overly rich or lean air-fuel mixture, not a
sticking valve. A stick- ing valve will cause the vacuum gauge needle to move rapidly up
and down. Answer c is not correct because neither technician is correct.
✔✔Two technicians are discussing a cylinder power balance test. Technician A says
the more the engine RPM drops, the weaker the cylinder. Technician B says that all
cylinder RPM drops should be within 50 RPM of each other. Which technician is
correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B - ✔✔The correct answer is b. Technician B only is correct. All
cylinders should drop the same (within 50 RPM) when they are canceled or grounded
out. This indicates that each cylinder was contributing an equal amount of the operation
of the engine. If a cylinder drops the RPM less than others, the cylinder is weak.
Technician A is not correct because the more the engine RPM drops when a cylinder is
canceled, the more that cylinder is contributing to the operation of the engine. Answers
c and d are not correct because only Technician B is correct.
✔✔A cylinder leakage (leak-down) test indicates 30% leakage, and air is heard coming
out of the air inlet. Technician A says that this is a normal reading for a slightly worn
engine. Technician B says that one or more intake valves are defective. Which
technician is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B - ✔✔The correct answer is b. A leakage of 30% is excessive and if
air is heard escaping from the engine air inlet, then one or more intake valves must be
leaking. It is also possible that the cylinder being tested is not at TDC on the
compression stroke. If the cylinder were at TDC of the exhaust stroke, both intake and
exhaust valves would be open and air would also be heard coming from the tailpipe.
Technician A is not correct because 30% leakage is too much for a slightly worn engine.
Leakage should not exceed 20%. Answers c and d are not correct because only
Technician B is correct.
✔✔During a cylinder leakage (leak-down) test, air is noticed coming out of the oil fill
opening. Technician A says that the oil filter may be clogged. Technician B says that the
piston rings may be worn or defective. Which technician is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B - ✔✔The correct answer is b. Technician B is correct because if the
piston rings were worn (or broken), compressed air could escape past the rings and
, flow into the crankcase. The air would then escape from the engine through the oil
drain-back holes and other openings in the block and eventually be heard at the oil fill
opening. Technician A is not correct because the oil filter is not being tested and the
compressed air entering the combustion chamber could not get into or past the oil filter.
Answers c and d are not correct because only Technician B is correct.
✔✔The low oil pressure warning light usually comes on ______________.
a. whenever an oil change is required
b. whenever oil pressure drops dangerously low (3 to 7 psi)
c. whenever the oil filter bypass valve opens
d. whenever the oil filter anti-drain-back valve opens - ✔✔The correct answer is b. The
oil pressure light comes on whenever the pressure drops to between 3 and 7 psi.
Answer a is not correct because the oil pressure light is not the same as the amber
"change oil soon" light. Answer c is not correct because there is no indication when the
bypass valve opens, which often occurs when the oil is cold or the oil filter is dirty and
creates a restriction. Answer d is not correct because this valve simply keeps oil from
draining back into the oil pan after the engine stops running.
✔✔Two technicians are discussing a compression test. Technician A says that the
engine should be cranked over with the pressure gauge installed for "3 puffs."
Technician B says that the maximum dif- ference between the highest-reading cylinder
and the lowest-reading cylinder should be 20%. Which technician is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B - ✔✔The correct answer is b. Technician B is correct because the
maximum difference, as specified by most vehicle manufacturers, is 20%. If the highest
reading is 160 psi, then the lowest cylinder com- pression should be greater than 128
psi (160 × 20% = 32 psi. 160 psi - 32 psi = 128 psi). Technician A is not correct because
the engine should be cranked through at least four compression events or 4 to 5 "puffs"
(not 3 "puffs"). Answers c and d are not correct because only Technician B is correct.
✔✔A compression test gave the following results:cylinder #1 = 155, cylinder #2 = 140,
cylinder #3 = 110, cylinder #4 = 105. Technician A says that a defective (burned) valve
is the most likely cause. Technician B says that a leaking head gasket could be the
cause. Which technician is correct?
a. A only
b. B only
c. Both A and B
d. Neither A nor B - ✔✔The correct answer is b. Technician B is correct because if the
head gasket were leaking between cylinder number 3 and 4, the compression on these
cylinders would be lower than normal. The defec- tive gasket would allow compression
to escape to the adjacent cylinders. Technician A is not correct because a burned valve
