OBD Systems & Diagnostics Flashcards
7 cards from real SCT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 OBD Systems & Diagnostics flashcards as text
What does OBD stand for in the context of vehicle emissions testing?
Answer: On-Board Diagnostics
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.
Which OBD generation became mandatory for all gasoline-powered light-duty vehicles sold in the United States starting with model year 1996?
Answer: OBD II
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.
Which OBD II readiness monitor specifically checks the integrity of the fuel tank vapor recovery system?
Answer: EVAP monitor
The EVAP (Evaporative Emission Control System) monitor checks for leaks and proper functioning of the fuel vapor recovery system to prevent hydrocarbon emissions.
What does it mean when an OBD II readiness monitor shows a status of 'not ready' or 'incomplete'?
Answer: The vehicle's computer has not yet completed its self-test for that system
'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.
In California, how many OBD II readiness monitors may show 'not ready' for a 2000 model year vehicle to still pass the smog inspection?
Answer: Two monitors may be incomplete
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.
What is the Malfunction Indicator Lamp (MIL) commonly known as to most vehicle owners?
Answer: Check Engine light
The MIL is commonly known as the 'Check Engine' light (some manufacturers label it 'Service Engine Soon'), and its illumination indicates the OBD II system has detected an emission-related fault.
What happens to a vehicle's OBD II readiness monitors when a technician clears diagnostic trouble codes using a scan tool?
Answer: All monitors reset to 'not ready' status
Clearing DTCs with a scan tool resets all OBD II readiness monitors to 'not ready,' requiring the vehicle to complete sufficient drive cycles before monitors return to ready status.