CEI Evaporative Emission Control Systems 3

Question 1

Why is the fuel cap the first component an inspector should check when diagnosing a P0440 or P0455 code?

Accepted Answer

A loose, missing, or faulty fuel cap is the most common cause of large EVAP leaks

Answer

The fuel cap controls canister purge flow rate

Answer

The fuel cap houses the FTP sensor

Answer

Fuel cap faults trigger P0440 before any other EVAP codes

Question 2

What is the significance of the OBD II 'two-trip' detection requirement for most EVAP codes?

Accepted Answer

The fault must be detected on two consecutive drive cycles before the MIL is illuminated

Answer

The vehicle must complete two full tanks of fuel before setting a code

Answer

Two separate sensors must independently confirm the fault

Answer

Two technicians must verify the fault before reporting it

Question 3

Which tool is specifically used to verify the sealing integrity of a vehicle's fuel cap during an emissions inspection?

Accepted Answer

Fuel cap pressure tester

Answer

Infrared thermometer

Answer

Oscilloscope

Answer

Exhaust gas analyzer

Question 4

How does cold ambient temperature affect EVAP system monitor readiness on an OBD II vehicle?

Accepted Answer

EVAP monitors may not run if ambient temperature is below the PCM threshold (often around 40°F / 4°C)

Answer

Cold temperatures accelerate the completion of EVAP readiness monitors

Answer

EVAP monitors run independently of temperature

Answer

Cold temperatures cause the vent valve to remain open, enabling faster testing

Question 5

What does it mean when an emissions inspection report shows the EVAP monitor as 'not ready' (incomplete)?

Accepted Answer

The PCM has not yet completed the EVAP self-test during this drive cycle set

Answer

The vehicle passed the EVAP test with no faults found

Answer

The EVAP system has a confirmed fault and set a pending code

Answer

The vehicle does not have an EVAP system installed

Question 6

Which EVAP system fault is most likely to cause a rich running condition and poor fuel economy in addition to an EVAP code?

Accepted Answer

Purge valve stuck open at idle

Answer

Cracked charcoal canister body

Answer

Vent valve stuck closed during normal driving

Answer

FTP sensor disconnected

Question 7

Under California's Enhanced EVAP (OBD II) inspection criteria, a vehicle will fail if the EVAP monitor shows 'not ready' AND which of the following is also true?

Accepted Answer

The vehicle has more than two other monitors showing 'not ready'

Answer

The vehicle was manufactured before 1996

Answer

The fuel level is above 50%

Answer

The vehicle's battery was recently disconnected, which is the suspected cause