P1134

DTC P1134 Oxygen Sensor 1 (O2S1) Transition Ratio

Circuit Diagram:

Circuit Description
The Engine Control Module (ECM) monitors the Oxygen Sensor 1 (O2S1) activity for 100 seconds after closed loop and stoichiometric operation have been established. During the monitoring period the ECM counts the number of times that the O2S1 responds from rich to lean and adds the amount of time it took to complete all transitions. With this information, an average time for all transitions can be determined. The ECM then divides the -to-lean average by the lean-to-rich average to obtain the ratio. If the O2S1 transition time ratio is not within the range, Diagnostic Trouble Code (DTC) P1134 will be set, indicating that the O2S1 is not responding as expected to changes in exhaust oxygen content.

Conditions for Setting the DTC
- O2S1 rich-to-lean and lean-to rich transition ratio is out of specification (between 0.3 and 4.7).
- Closed Loop stoichiometry.
- Engine Coolant Temperature (ECT) is greater than 70 °C (158 °F).
- System voltage is greater than 10 volts.
- Engine run time is greater than 60 seconds.
- Purge Duty Cycle (DC) is less than 20%.
- Engine speed is between 1600 and 4300 rpm.
- Calculated airflow is between 9 and 40 g/sec.
- DTCs P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0131, P0132, P0134, P1167, P0171, P1171, P0172, P0201, P0202, P0203, P0204, P0300, P0336, P0337, P0351, P0352, P0401, P0402, P0404, P0405, P0406, P0502, P0506, P0507, P1404, P1441, and P0443 are not set.
- 2 second delay after conditions are met.

Action Taken When the DTC Sets
- The Malfunction Indicator Lamp (MIL) will illuminate.
- The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers.
- A history DTC is stored.
- The vehicle will operate in Open Loop.

Conditions for Clearing the MIL/DTC
- The MIL will turn off after four consecutive ignition cycles in which the diagnostic runs without a fault.
- A history DTC will clear after 40 consecutive warm-up cycles without a fault.
- The DTC(s) can be cleared by using the scan tool.
- Disconnecting the ECM battery feed for more than 10 seconds.

Diagnostic Aids
A malfunction in the O2S1 ignition feed or ground circuit may cause a DTC P1134 to set. Check O2S1 circuitry for intermittent faults or poor connections. If connections and wiring are OK and DTC P1134 continues to set, replace the O2S1. Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how open the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

Test Description
Number(s) below refer to the step number(s) on the Diagnostic Chart.
3. A condition that affects pre-converter and post-converter oxygen sensors indicates probable contamination. To avoid damaging replacement sensors, correct the condition which caused the contamination before replacing the affected sensors.
5. This step checks for conditions which may cause the oxygen sensor to appear faulty. Correct any of the described conditions if present.
8. To avoid damaging replacement sensors, correct the condition which caused the contamination before replacing the affected sensors.

Step 1:

Step 2 - 15: