CEI CEI Vehicle Inspection & OBD Systems 2 — Questions and Answers
Question 1: During a visual inspection for emission testing, an inspector notices the catalytic converter has been removed and replaced with a straight pipe. What is the correct action?
- Fail the vehicle for tampering with required emission control equipment (Correct answer)
- Pass the vehicle if the OBD monitors are ready
- Issue a warning and schedule a re-inspection in 30 days
- Pass the vehicle if tailpipe readings are within limits
Correct answer: Fail the vehicle for tampering with required emission control equipment
Removal of required emission control equipment such as a catalytic converter constitutes tampering and is grounds for automatic failure of the emission inspection.
Question 2: What is the purpose of the evaporative emission control (EVAP) system in a vehicle?
- To capture and store fuel vapors from the fuel tank and prevent them from escaping into the atmosphere (Correct answer)
- To cool the exhaust gases before they exit the tailpipe
- To recirculate exhaust gases back into the engine intake
- To filter particulate matter from the engine air intake
Correct answer: To capture and store fuel vapors from the fuel tank and prevent them from escaping into the atmosphere
The EVAP system captures hydrocarbon fuel vapors from the fuel tank and routes them to the engine to be burned, preventing VOC emissions from venting to the atmosphere.
Question 3: Which vehicle model year marked the federal requirement for OBD-II compliance on all new light-duty gasoline passenger cars sold in the US?
- 1996 (Correct answer)
- 1988
- 2000
- 1994
Correct answer: 1996
The US EPA required all new light-duty gasoline passenger cars to be OBD-II compliant beginning with model year 1996, under 40 CFR Part 86.
Question 4: What does a flashing or blinking MIL (Check Engine Light) during an OBD-II inspection indicate?
- A misfire severe enough to damage the catalytic converter is occurring (Correct answer)
- The vehicle's OBD system is performing a self-test
- The vehicle passed the emission test with minor issues
- The battery voltage is critically low
Correct answer: A misfire severe enough to damage the catalytic converter is occurring
A flashing MIL indicates an active, severe misfire that could cause catalytic converter damage, which is a more urgent condition than a steady MIL.
Question 5: In an OBD-II inspection, what is a 'freeze frame' data record?
- A snapshot of sensor data captured at the moment a DTC was set (Correct answer)
- A video recording of the MIL activation event
- A static calibration image stored in the ECU memory
- A printout of all historical emission test results
Correct answer: A snapshot of sensor data captured at the moment a DTC was set
Freeze frame data is a snapshot of key engine parameters (RPM, load, fuel trim, etc.) that the ECU saves at the instant a Diagnostic Trouble Code is detected.
Question 6: A vehicle that recently had its battery disconnected may fail an OBD inspection for which reason?
- Readiness monitors will be reset and show 'not ready' until drive cycles are completed (Correct answer)
- The MIL will automatically illuminate after battery reconnection
- The ECU will store a false P0600 network fault code
- The fuel trim data will be permanently erased causing rich running
Correct answer: Readiness monitors will be reset and show 'not ready' until drive cycles are completed
Disconnecting the battery resets the OBD-II system, clearing readiness monitors, which must be reset by completing specific drive cycles before an inspection.
CEI CEI Vehicle Inspection & OBD Systems 2
During a visual inspection for emission testing, an inspector notices the catalytic converter has been removed and replaced with a straight pipe.
What is the correct action?