Engine Performance II Final Prep with
Correct Solutions 2025
A P0171 Bank 1 System Too Lean and a P0303 Cylinder #3 Misfire Detected DTC are
present. Technician A says the Bank 1 fuel trim values should be checked. Technician
B says that the Misfire Load and RPM can be used to duplicate the specific misfire
conditions present. Who is correct? - ANSWER-Both
A P0172 (Bank 1 System Too Rich) DTC is stored in Pending status. Technician A says
this DTC will set as a Permanent DTC during the 2nd-trip failure. Technician B says the
P0172 is part of the Fuel Monitor. Who is correct? - ANSWER-Both
A P0340 Camshaft Position Sensor Circuit Malfunction and a P0301 Cylinder 1 Misfire
DTC are present. Technician A says to diagnose the P0301 DTC first. Technician B
says to diagnose the P0340 DTC first. Who is correct? - ANSWER-Tech B
A Technician diagnosing a lack of power concern with no DTCs notices the combined
fuel trim value at 18%. Technician A says that without a DTC fuel trim values are
considered normal. Technician B says that drivability problems may present themselves
far before fuel trims exceed DTC threshold conditions. Who is correct? - ANSWER-Tech
B
A Technician notices a sudden shift in the long term fuel trim values as the engine is
accelerated. Technician A says that a sudden shift always indicates a malfunction.
Technician B says that a sudden shift in long term fuel trim values may be normal if it is
the result of learned correction values being added to the basic injector duration. Who is
correct? - ANSWER-Tech B
A Technician observes the following misfire data during diagnosis:
AFS voltage B1S1: 3.29v
AFS voltage B2S1: 3.64v
O2S B1S2: 0.456v
O2S B2S2: 0.013v
Technician A says there is a lean misfire present. Technician B says the problem is
indicated on Bank 1. Who is correct? - ANSWER-Tech A
A Technician observes the following Techstream data during an engine misfire
diagnosis after the engine has been running for a prolonged period of time.
ECT: 134 F
IAT: 98 F
Engine speed: 763 rpm
MAF: 2.67 gm/sec
Technician A says the CKP sensor should be checked. Technician B says the ECT
sensor may be biased and should be checked. Who is correct? - ANSWER-Tech B
, A vehicle has a faulty ignition coil that is not producing a spark. Technician A says this
will produce excess CO in that cylinder. Technician B says that CO can only be
produced if combustion occurs. Who is correct? - ANSWER-Tech B
A vehicle has higher than normal idle and no vacuum leaks are present. Technician B
says the PCV line should be blocked off to see if excessive PCV flow is the cause.
Technician B says crankcase pressure will be forced through the breather hose when
the PCV line is blocked. Who is correct? - ANSWER-Both
During a catalyst temperature differential test a Technician observes an outlet
temperature that is 98°F hotter than the inlet temperature. Technician A says the
catalyst should be replaced. Technician B says the tests results are inconclusive and
should not be used to condemn the catalytic converter. Who is correct? - ANSWER-
Tech B
During a cold start on a vehicle with a P0455 (Large Leak) and a P0441 (Incorrect
Purge Flow) a Technician observes the Short FT parameter drop to -14.67% over a
period of 10s and then rise to +18.12%. Technician A says the purge valve may be
stuck closed. Technician B says the large leak DTC should be diagnosed. Who is
correct? - ANSWER-Neither
During a PCV system functional check the engine RPM drops ~20 RPM. Technician A
says this indicates too little flow. Technician B says this indicates too much flow. Who is
correct? - ANSWER-Tech A
During active testing of the EGR system the MAP sensor displays a value of 52kPa.
Technician A says the MAP sensor indicates good EGR flow. Technician B says the
MAP sensor value should be higher than 95kPa. Who is correct? - ANSWER-Neither
During air injection diagnosis with the B1 pump on and the ASV off the pressure sensor
is pulsating and low. Technician A says the air switching valve may be bad. Technician
B says the air pump may be failing. Who is correct? - ANSWER-Tech B
During an inspection of the catalyst a rattle is heard while tap testing the catalyst
assembly. Technician A says the catalyst can be repaired. Technician B says that a
loose substrate will require replacement. Who is correct? - ANSWER-Tech B
During diagnosis of the catalyst a technician observes the downstream sensor at .01V
1.5 seconds after the a/f ratio is commanded lean using a Techstream. Technician A
says that the catalyst is not storing oxygen efficiently. Technician B says the O2S value
indicates a properly functioning catalyst. Who is correct? - ANSWER-Tech A
During EVAP monitoring a Technician observes the VPS value at -14.56mmHG during
stage three of the monitor. Technician A says the value indicates a small leak.
Technician B says it is not useful to view this value. Who is correct? - ANSWER-Neither
Correct Solutions 2025
A P0171 Bank 1 System Too Lean and a P0303 Cylinder #3 Misfire Detected DTC are
present. Technician A says the Bank 1 fuel trim values should be checked. Technician
B says that the Misfire Load and RPM can be used to duplicate the specific misfire
conditions present. Who is correct? - ANSWER-Both
A P0172 (Bank 1 System Too Rich) DTC is stored in Pending status. Technician A says
this DTC will set as a Permanent DTC during the 2nd-trip failure. Technician B says the
P0172 is part of the Fuel Monitor. Who is correct? - ANSWER-Both
A P0340 Camshaft Position Sensor Circuit Malfunction and a P0301 Cylinder 1 Misfire
DTC are present. Technician A says to diagnose the P0301 DTC first. Technician B
says to diagnose the P0340 DTC first. Who is correct? - ANSWER-Tech B
A Technician diagnosing a lack of power concern with no DTCs notices the combined
fuel trim value at 18%. Technician A says that without a DTC fuel trim values are
considered normal. Technician B says that drivability problems may present themselves
far before fuel trims exceed DTC threshold conditions. Who is correct? - ANSWER-Tech
B
A Technician notices a sudden shift in the long term fuel trim values as the engine is
accelerated. Technician A says that a sudden shift always indicates a malfunction.
Technician B says that a sudden shift in long term fuel trim values may be normal if it is
the result of learned correction values being added to the basic injector duration. Who is
correct? - ANSWER-Tech B
A Technician observes the following misfire data during diagnosis:
AFS voltage B1S1: 3.29v
AFS voltage B2S1: 3.64v
O2S B1S2: 0.456v
O2S B2S2: 0.013v
Technician A says there is a lean misfire present. Technician B says the problem is
indicated on Bank 1. Who is correct? - ANSWER-Tech A
A Technician observes the following Techstream data during an engine misfire
diagnosis after the engine has been running for a prolonged period of time.
ECT: 134 F
IAT: 98 F
Engine speed: 763 rpm
MAF: 2.67 gm/sec
Technician A says the CKP sensor should be checked. Technician B says the ECT
sensor may be biased and should be checked. Who is correct? - ANSWER-Tech B
, A vehicle has a faulty ignition coil that is not producing a spark. Technician A says this
will produce excess CO in that cylinder. Technician B says that CO can only be
produced if combustion occurs. Who is correct? - ANSWER-Tech B
A vehicle has higher than normal idle and no vacuum leaks are present. Technician B
says the PCV line should be blocked off to see if excessive PCV flow is the cause.
Technician B says crankcase pressure will be forced through the breather hose when
the PCV line is blocked. Who is correct? - ANSWER-Both
During a catalyst temperature differential test a Technician observes an outlet
temperature that is 98°F hotter than the inlet temperature. Technician A says the
catalyst should be replaced. Technician B says the tests results are inconclusive and
should not be used to condemn the catalytic converter. Who is correct? - ANSWER-
Tech B
During a cold start on a vehicle with a P0455 (Large Leak) and a P0441 (Incorrect
Purge Flow) a Technician observes the Short FT parameter drop to -14.67% over a
period of 10s and then rise to +18.12%. Technician A says the purge valve may be
stuck closed. Technician B says the large leak DTC should be diagnosed. Who is
correct? - ANSWER-Neither
During a PCV system functional check the engine RPM drops ~20 RPM. Technician A
says this indicates too little flow. Technician B says this indicates too much flow. Who is
correct? - ANSWER-Tech A
During active testing of the EGR system the MAP sensor displays a value of 52kPa.
Technician A says the MAP sensor indicates good EGR flow. Technician B says the
MAP sensor value should be higher than 95kPa. Who is correct? - ANSWER-Neither
During air injection diagnosis with the B1 pump on and the ASV off the pressure sensor
is pulsating and low. Technician A says the air switching valve may be bad. Technician
B says the air pump may be failing. Who is correct? - ANSWER-Tech B
During an inspection of the catalyst a rattle is heard while tap testing the catalyst
assembly. Technician A says the catalyst can be repaired. Technician B says that a
loose substrate will require replacement. Who is correct? - ANSWER-Tech B
During diagnosis of the catalyst a technician observes the downstream sensor at .01V
1.5 seconds after the a/f ratio is commanded lean using a Techstream. Technician A
says that the catalyst is not storing oxygen efficiently. Technician B says the O2S value
indicates a properly functioning catalyst. Who is correct? - ANSWER-Tech A
During EVAP monitoring a Technician observes the VPS value at -14.56mmHG during
stage three of the monitor. Technician A says the value indicates a small leak.
Technician B says it is not useful to view this value. Who is correct? - ANSWER-Neither
