P0134
DTC P0134 O2S CKT Insufficient Activity Sensor1
Circuit Description
The Powertrain Control Module (PCM) supplies a reference voltage of about 0.45 volt to the Oxygen Sensor (O2S). The O2S 1 voltage varies within a range of about 1.0 volt when the exhaust is rich, down to about 0.10 volt when the exhaust is lean.
Conditions For Running The DTC
- DTCs P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0171, P0200, P0300, P0301, P0302, P0303, P0304, P0335, P0440, P0442, P0446, P0506, P0507, P0601, P0602, or P1441 not set.
- Air flow is greater than 3 grams per second.
- Engine Coolant Temperature (ECT) is greater than 70 °C (158 °F).
- Throttle Position (TP) angle is between 4% and 56% for 20 seconds.
- Engine run time is greater than 30 seconds.
Conditions For Setting The DTC
O2S 1 voltage is between 399 mV and 499 mV for 125 seconds.
Action Taken When the DTC Sets
- The Malfunction Indicator Lamp (MIL) will illuminate after two consecutive ignition cycles in which the diagnostic runs with the malfunction active.
- The PCM will record the operating conditions at the time that the diagnostic fails. The Freeze Frame and Failure Records buffers will store this information.
- A history DTC stores.
Conditions for Clearing the MIL/DTC
- The MIL will turn off after 3 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
- A scan tool can clear the DTCs
Diagnostic Aids
- When the oxygen sensor pigtail wiring, connector or terminal are damaged, the entire oxygen sensor assembly must be replaced. Do not attempt to repair the wiring, the connector or the terminals. In order for the sensor to function properly, the O2S must have a clean air reference. This clean air reference is obtained by way of the oxygen sensor wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degrade the oxygen performance of the sensor.
- The normal scan tool voltage varies between 150 mV to 850 mV (0.15 volt to 0.85 volt) when in a Closed Loop. The DTC P0134 sets in approximately 88 seconds when the voltage remains between 0.407 volt and 0.509 volt. The system will go into an Open Loop in about 30 seconds.
Step 1:
Steps 2 - 4:
Steps 5 - 9:
Steps 10 - 13:
Test Description
The number(s) below refer(s) to the step number(s) on the Diagnostic Table.
1. The Powertrain OBD System Check prompts you to complete some of the basic checks and to store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The scan tool stores this data for later reference.
2. During the engine warm-up, the O2S 1 should warm-up and the voltage output should vary between 150 mV and 850 mV. When the O2S 1 voltage varies, the engine will go into a Closed Loop operation. This step determines if the O2S 1 sensor is operating properly.
4. This step will determine if the O2S 1 sensor is malfunctioning, or if the wiring or the PCM is the cause of the DTC P0134.
6. Use only a high impedance digital volt ohmmeter for this test. This test checks the continuity of O2S 1 sensor signal circuit and the O2S 1 sensor low circuit; if the O2S 1 sensor low circuit is open, and if the PCM voltage or the O2S 1 sensor signal circuit will be over 0.6 volt (600 mV).
8. Reprogram the replacement PCM and perform the crankshaft position system variation learn procedure. Refer to the latest Isuzu technical Communication System (ITCS) information for PCM programming and the CKP System Variation Learn Procedure for the crankshaft position system variation learn procedure.