SCT OBD Systems & Diagnostics

Question 1

What does OBD stand for in the context of vehicle emissions testing?

Accepted Answer

On-Board Diagnostics

Answer

OBD stands for On-Board Diagnostics, referring to the vehicle's built-in self-diagnostic and reporting capability managed by the vehicle's computer system.

Question 2

Which OBD generation became mandatory for all gasoline-powered light-duty vehicles sold in the United States starting with model year 1996?

Accepted Answer

OBD II

Answer

OBD II became federally mandated for all 1996 and newer light-duty gasoline vehicles sold in the United States, standardizing diagnostic communication and readiness monitoring.

Question 3

Which OBD II readiness monitor specifically checks the integrity of the fuel tank vapor recovery system?

Accepted Answer

EVAP monitor

Answer

The EVAP (Evaporative Emission Control System) monitor checks for leaks and proper functioning of the fuel vapor recovery system to prevent hydrocarbon emissions.

Question 4

What does it mean when an OBD II readiness monitor shows a status of 'not ready' or 'incomplete'?

Accepted Answer

The vehicle's computer has not yet completed its self-test for that system

Answer

'Not ready' means the ECM has not yet completed its self-diagnostic test for that monitor, usually because sufficient drive cycles have not occurred since the battery was disconnected or codes were cleared.

Question 5

In California, how many OBD II readiness monitors may show 'not ready' for a 2000 model year vehicle to still pass the smog inspection?

Accepted Answer

Two monitors may be incomplete

Answer

California allows up to two incomplete readiness monitors for 1996–2000 model year OBD II vehicles, while 2001 and newer vehicles are only allowed one incomplete monitor.

SCT - Smog Check Technician Certification Practice Test

SCT - Smog Check Technician Certification Practice Test

SCT OBD Systems & Diagnostics