Exam 10: Strategies of on Board Diagnostic Non Continuous Monitors

Which monitor is used to detect malfunctions that will affect engine coolant temperature and prevent the engine from reaching normal operating temperature?

A vehicle is brought in for repair with the complaint of poor fuel economy. A diagnostic scan tool is attached to the DLC with the vehicle at operating temperature, and the technician determines that the precatalyst oxygen sensor voltage is biased high, the injector pulse width is long, and both STFT and LTFT are high. All of the following conditions could cause this EXCEPT:

When the PCV system removes blowby gases from the engine crankcase, to what system are the removed gases directed, and what happens to the gases sent to that system?

In order for the MIL to be extinguished, two consecutive good global trips must be seen by the PCM.

The EGR monitor is an intrusive test, and the customer may notice an rpm fluctuation while the test is taking place.

An evaporative emissions system large leak or no purge flow could be caused by all of the following EXCEPT:

When is the optimum time for the maximum EGR system flow rate?

As an oxygen sensor degrades, what happens to its switch rate compared to that of a properly functioning sensor?

Technician A says that a fuel-saturated evaporative emissions canister will cause negative STFT numbers. Technician B says that a fuel-saturated evaporative emissions canister will cause negative LTFT numbers. Who is correct?

Explain the purpose of the catalyst efficiency monitor.

The enhanced system must be capable of detecting a leak as small as 0.060 inch (1.5 mm).

To determine the efficiency of the catalytic converters, the PCM uses a complex software program and data look-up tables when the catalyst monitor is run.

Explain the function of the heated oxygen sensor monitor.

What does OBD II call the specific conditions that must be met before each monitor will run?

OBD II requires an EGR system monitor that will test all of the following EXCEPT:

The catalyst efficiency monitor compares the signals from what oxygen sensors?

Explain the function of the exhaust gas recirculation system monitor.

Explain the function of the evaporative emissions system monitor.

Why do we need an EGR valve to recirculate exhaust gases that have already gone through combustion back into the combustion chamber?

The PCM continuously tests the electrical integrity of the system and monitors the EGR flow rate twice per trip.