P1154

CIRCUIT DESCRIPTION
Use this diagnostic test in conjunction with the HO2S (Bank 2, Sensor 1) slow response diagnostic test (P0153). The ratio of the response times that were calculated are compared to the calibrated limits. If the number of both the lean to rich transitions (switches) and the rich to lean transitions were both zero, then the ratios will set to 0. Otherwise, the ratio is calculated based on which average response time was greater. DTC P1154 is a type B DTC.

CONDITIONS FOR SETTING THE DTC
The following conditions sets the DTC:

^ No fuel trim DTCs.
^ L/R switches less than 30.
^ R/L switches less than 30.
^ No TP sensor DTCs.
^ No Evaporative Emissions (EVAP) DTCs.
^ No IAT sensor DTCs.
^ No MAP DTCs.
^ No EGR DTCs.
^ No ECT sensor DTCs.
^ The DTC P0155 is not set.
^ Closed Loop.
^ HO2S voltage between 0.300 volts and 0.600 volts.
^ Throttle position greater than 10% but less than 20%.
^ The average response time calculations completed for this ignition cycle.
^ The ratio of HO2S LR/RL transitions is less than expected.

ACTION TAKEN WHEN THE DTC SETS
The VCM turns on the MIL (Malfunction Indicator Lamp) after 2 consecutive test failures.

The VCM records the operating conditions at the time the diagnostic fails. The Freeze Frame and Failure Records store this information.

CONDITIONS FOR CLEARING THE MIL/DTC
The VCM turns the MIL off after 3 consecutive drive trips that the diagnostic runs and does not fail. A Last Test Failed (current) DTC clears when the diagnostic runs and does not fail.

A History DTC clears after 40 consecutive warm-up cycles with no failures of any emission related diagnostic test.

The VCM battery voltage is interrupted.

The scan tool Clear Info function is used.

DIAGNOSTIC AIDS
Never solder the HO2S wires. For a proper wire and connector repair refer to Wiring Repairs.

TEST DESCRIPTION
The numbers below refer to the step numbers in the diagnostic table.

2. This step checks to see if the other causes of this DTC have already been diagnosed.
3. Diagnose other DTCs first because they may have set this DTC.
4. With the engine running warm, coolant at least 85°C (185°F) and at fast idle, the HO2S voltage should rapidly swing above 0.60 volts and below 0.30 volts.
6. This step checks to see if the Oxygen sensor voltage is swinging between rich and lean very slowly or not at all.
9. This step checks for causes of the HO2S failure. If the sensor is replaced without finding the cause of the contamination, the replacement sensor may become contaminated.