Circuit Description
The Powertrain Control Module (PCM) supplies a voltage of about 0.45 volt between the O2S signal and the ground circuit. The Oxygen Sensor (O2S 1) varies the voltage within a range of about 1 volt if the exhaust is rich, down through about 0.10 volt if the exhaust is lean.
The sensor is like an open circuit and produces no voltage when below 315°C (600°F). An open sensor circuit or a cold sensor causes an Open Loop operation.
If there is damage to the oxygen sensor pigtail wiring, the connector or the terminal, replace the entire oxygen sensor assembly. Do not attempt to repair the wiring, the connector or the terminals. The sensor must have a clean air reference provided in order to function properly. This clean air reference is obtained by way of the oxygen sensor wire(s). Any attempt to repair the wires, the connectors or the terminals could result in the obstruction of the air reference and degrade the oxygen sensor performance. Refer to Heated Oxygen Sensor (O2S) Repair.
Conditions For Setting The DTC
| • | DTC's P0106, P0107, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0200, P0300, P0301, P0302, P0303, P0304, P0506, P0507, P1406, P1441 not set. |
| • | Engine run time is greater than 25 seconds. |
| • | Engine Coolant Temperature (ECT) is greater than 70° C (158° F). |
| • | Air/fuel ratio is between 14.5:1 and 14.7:1. |
| • | Engine is operating in Closed Loop. |
| • | Throttle Position (TP) angle is between 8 % and 50 % (manual trans.). |
| Or |
| • | Throttle Position (TP) angle is between 5 % and 50 % (auto trans.). |
| • | Engine has met the above conditions for 20 seconds. |
| • | O2S 1 voltage is greater than 1042 mV for 50 seconds. |
| Or |
| • | O2S 1 voltage is greater than 738 mV for 50 seconds while in deceleration mode. |
Action Taken When the DTC Sets
| • | The Malfunction Indicator Lamp (MIL) will illuminate. |
| • | The PCM will record the operating conditions at the time that the diagnostic fails. This information will store in the Freeze Frame and Failure Records buffers. |
| • | A history DTC stores. |
| • | The coolant fan turns ON. |
| • | The vehicle will operate in an Open Loop operation. |
Conditions for Clearing the MIL/DTC
| • | The MIL will turn OFF after three 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 MIL/DTCs can be cleared by using the scan tool. |
Diagnostic Aids
The DTC P0132 or rich exhaust is most likely caused by one of the following items:
| • | Fuel pressure - The system will go rich if fuel pressure is to high. The PCM can compensate for some increase, however, if it gets too high, a DTC P0132 will be set. See Fuel System Diagnosis . |
| • | Leaking injector - A leaking or faulty injector can cause the system to go rich causing a DTC P0132. See Fuel Injector Solenoid Coil Test . |
| • | Electronic Ignition (EI) shielding - An open ground CKT 453 may result in EMI or induced electrical noise. The PCM looks at this noise as Crankshaft Position (CKP) sensor pulses. The additional pulses result in a higher than actual engine speed signal. The PCM then delivers too much fuel causing the system to go rich. The engine tachometer will also show higher than actual engine speed which can help in diagnosing this problem. |
| • | MAP sensor - An output that causes the PCM to sense a higher than normal manifold pressure (low vacuum) can cause the system to go rich. Disconnecting the MAP sensor will allow the PCM to set a fixed value for the MAP sensor. Substitute a different MAP sensor if the rich condition is gone while the sensor is disconnected. |
| • | Pressure regulator - Check for a leaking fuel pressure regulator diaphragm by checking for the presence of liquid fuel in the vacuum line to the regulator. |
| • | TP sensor - An intermittent TP sensor output will cause the system to go rich due to a false indication of the engine accelerating. |
| • | O2S 1 contamination - Inspect O2S 1 for silicone contamination from fuel or use of improper RTV sealant. The sensor may have a white powdery coating and result in a high but false voltage signal (rich exhaust indication). The PCM will then reduce the amount of fuel delivered to the engine causing a severe surge or driveability problem. |
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
-
The Powertrain OBD System Check prompts the technician to complete some basic checks and 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 fault occurred. The information is then stored in the scan tool for later reference.
-
This step determines if DTC P0132 is the result of a hard failure or an intermittent condition. It may be necessary to operate the vehicle within the Freeze Frame conditions and Conditions for Setting the DTC in order to duplicate the fault detected by the PCM.
-
This step simulates a DTC P0131. If the PCM senses the change, the PCM and wiring are OK.
-
Replacement PCM's must be reprogrammed. Refer to the latest Techline information for programming procedures.
-
If no faults have been found at this point and no additional DTC's were set, refer to Diagnostic Aids for additional checks and information.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | |||
Does the O2S 1 voltage remain above the specified value? | 851 mV | |||
3 |
Does the O2S 1 voltage stay above the specified value? | 851 mV | ||
Does the scan tool indicate the O2S 1 voltage below the specified value? | 350 mV (.35 V) | |||
5 | Check the O2S 1 sensor signal circuit for a short to voltage and repair as necessary. Was a repair necessary? | -- | ||
Replace the PCM. Is the action complete? | -- | -- | ||
7 |
Does the scan tool indicate that this diagnostic ran and passed. | -- | ||
Check if any additional DTC's are set. Are any DTC's displayed that have not been diagnosed? | -- | Go to applicable DTC table | System OK, Refer to Diagnostic Aids |
