Advanced Diagnostics

Advanced Diagnostics

DTC P0133: Air/Fuel Ratio (A/F) Sensor (Sensor 1) Malfunction/Slow Response (Engine Type: K20Z3)






General Description
The air/fuel ratio (A/F) sensor (sensor 1) has a linear signal output in relation to the oxygen concentration. The engine control module (ECM) computes the air/fuel ratio from the A/F sensor output voltage and uses fuel feedback control to improve exhaust emissions. The ECM measures the response characteristics against the A/F sensor output. If the total A/F sensor output is less than the specified value within a specified time, it detects a deteriorated response and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type, OBD Status






Enable Conditions






Malfunction Threshold
The total A/F sensor output value is 37 or less in 8 seconds.

Driving Pattern






1. Start the engine. Hold the engine speed at 3,000 rpm without load (in neutral) until the radiator fan comes on.
2. Drive the vehicle at a steady speed up to 25 mph (40 km/h), for at least 5 minutes.
3. Then, drive immediately at a steady speed of 33 mph (52 km/h) or more and engine speed between 1,500 - 3,300 rpm for at least 8 seconds.

- Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.

Diagnosis Details

Conditions for illuminating the MIL
When a malfunction is detected during the first drive cycle, a Temporary DTC is stored in the ECM memory. If the malfunction recurs during the next (second) drive cycle, the MIL comes on and the DTC and the freeze frame data are stored.

Conditions for clearing the MIL
The MIL will be cleared if the malfunction does not recur during three consecutive trips in which the diagnostic runs. The MIL, the DTC, the Temporary DTC, and the freeze frame data can be cleared by using the scan tool Clear command or by disconnecting the battery.