Deck 7: Understanding Obd Ii

Question 1

The newest global OBD II mode, mode $0A, was required on 100% of U.S. vehicles by the 2012 model year. Mode $0A is a scan tool request for:

A) calculated fuel economy data
B) pending DTCs
C) confirmed DTCs
D) permanent DTCs

Answer 1

D

Question 2

On an OBD II vehicle, how many times must the PCM see a fault present before it will illuminate the MIL (for most faults)?

A) Two
B) Three
C) Four
D) Five

Answer 2

A

Question 3

If there is an exhaust leak ahead of the rear HO₂S, or if the rear HO₂S is faulty, which of the following can result?

A) An inability to run the catalytic converter monitor properly
B) Improper control of the engine's air/fuel ratio resulting in an incorrect lambda value
C) The production of too much CO₂
D) Both A and B

Answer 3

D

Question 4

On an OBD II vehicle, following the illumination of the MIL, the MIL will stay lit until the system or component passes the same test for _____ consecutive trips.

A) two
B) three
C) four
D) five

Question 5

The OBD II data link connector (DLC) is being discussed. Technician A says terminal fourteen is always battery positive. Technician B says terminals four and five are always grounds. Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 6

An OBD II PCM will erase confirmed DTCs from memory if it does not see the problem occur again for:

A) 40 minutes of engine operation
B) 40 restarts of the engine
C) 40 warm-up and cool-down cycles of the engine
D) 40 miles of vehicle travel

Question 7

Which of the following statements is correct?

A) Mode $01 is a scan tools request to access the data stream.
B) Mode $06 is a scan tools request to obtain the test results of non-continuous monitors
C) Both A and B are correct
D) Neither A nor B is correct

Question 8

In addition to flashing the MIL, how do many OBD II PCMs react to a "Type A" (severe) cylinder misfire?

A) The PCM turns off the spark for the misfiring cylinder.
B) The PCM turns off the fuel injector for the misfiring cylinder.
C) The PCM increases fuel delivery for the misfiring cylinder in order to allow the extra unburned fuel to cool the catalytic converter.
D) The PCM energizes an oil solenoid which allows a specially designed lifter to collapse, resulting in keeping the exhaust valve closed so as to block exhaust flow from the misfiring cylinder.

Question 9

Technician A says that a monitor readiness status that is indicated as "Complete" means that the monitor has been identified by the PCM as a "PASS, NO PROBLEM FOUND": Technician B says that a monitor readiness status that is indicated as "Incomplete" could be a reason why a DTC has not been set for a failure and the appropriate drive cycle should be run.  Then DTCs should be rechecked. Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 10

On a 2001 model year or newer vehicle, the PCM is required to turn on the MIL and store a DTC if an EVAP system leak is identified that is larger than:

A) 1 in
B) 0.100 in
C) 0.040 in
D) 0.020 in

Question 11

On GM OBD II vehicles, the PCM tests EGR operation by turning EGR on and off and monitoring which of the following sensors?

A) MAP sensor
B) TPS
C) ECT sensor
D) VSS

Question 12

Prior to erasing DTCs on an OBD II vehicle, a scan tool should be used to perform all of these tasks EXCEPT :

A) retrieve memory DTCs
B) record freeze frame data
C) activate all active command modes
D) check monitor readiness status

Question 13

Cold start emissions reduction is being discussed. Technician A says that a strategy to reduce them is to delay the PCM going into close loop mode. Technician B says that an applicable strategy is to retard ignition timing during engine warmup. Who is correct?

A) Technician A
B) Technician B
C) Both A and B
D) Neither A nor B

Question 14

The PCM will compare input values to each other when running which OBD II monitor?

A) Misfire Monitor
B) Comprehensive Components Monitor
C) O₂ Sensor Monitor
D) Cylinder Imbalance Monitor

Question 15

What requirement(s) is/are mandated by OBD II?

A) All manufacturers must redesign their engine control systems so as to operate identically in all respects and according to an EPA-designed engine control system.
B) The PCM must turn on the MIL if component and/or system inefficiency results in emission levels exceeding 1.5 times the FTP cut-point.
C) The PCM must turn on the MIL if component and/or system inefficiency results in emission levels exceeding two times the FTP cut-point.
D) Both A and C

Question 16

The PCM will purposefully pulse the fuel injectors abnormally rich and lean when running which OBD II monitor?

A) Misfire Monitor
B) Comprehensive Components Monitor
C) O₂ Sensor Monitor
D) Cylinder Imbalance Monitor

Question 17

Emissions that escape during refueling are being discussed. Technician A says an on-board refueling vapor recovery system may be used. Technician B says a fuel tank bladder may be used. Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 18

The newest OBD II monitor, introduced in 2008 and required under OBD II standards to be present on all U.S. vehicles by 2014, is the:

A) Intake Air Temperature Monitor
B) Muffler Efficiency Monitor
C) Cyclic Redundancy Check Monitor
D) Cylinder Imbalance Monitor

Question 19

All of these organizations continue to work together to update and enhance the on-board diagnostic standards and regulations EXCEPT the:

A) OBD
B) SAE
C) EPA
D) CARB

Question 20

An OBD II PCM is able to detect engine misfire by monitoring:

A) engine vacuum
B) engine RPM
C) engine load
D) vehicle speed