Circuit Description
Oxygen sensors (O2S) are used for fuel control and post catalyst monitoring. Each O2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The O2S must reach operating temperature to provide an accurate voltage signal. A heating element in O2S 2 minimizes the time required for the sensor to reach operating temperature. The powertrain control module (PCM) supplies the O2S with a reference, or bias, voltage of about 450 mV. When the engine is first started the PCM operates in open loop, ignoring the O2S voltage signal. Once the O2S reaches operating temperature and Closed Loop is achieved, the O2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage. High O2S voltage indicates a rich exhaust stream. Low O2S voltage indicates a lean exhaust stream. If the PCM detects that O2S 1 voltage stays above a specified value, DTC P0132 will set.
Conditions For Running The DTC
Rich Test Enable:
| • | DTCs P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0171, P0172, P0201-P0204, P0300, P0301-P0304, P0336, P0440, P0446, P0452, P0453, P0506, P0507, P0601, P0602, or P1441 are not set. |
| • | The ECT Sensor parameter is more than 70°C (158°F). |
| • | The Engine Run Time parameter is more than 10 seconds. |
| • | The TP Sensor parameter is between 8-50 percent. |
| • | The Fuel Level Sensor parameter is more than 10 percent. |
| • | The Loop Status parameter is closed. |
| • | The Ignition 1 Signal parameter is more than 10 volts. |
| • | The MAP Sensor parameter is more than 10 kPa. |
| • | The above conditions are met for 3.8 seconds. |
OR
Decel. Fuel Cutoff Test Enable:
| • | DTCs P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0171, P0172, P0201-P0204, P0300, P0301-P0304, P0336, P0440, P0446, P0452, P0453, P0506, P0507, P0601, P0602, or P1441 are not set. |
| • | The Loop Status parameter is closed. |
| • | The Decel. Fuel Cutoff is Active for more than 2.5 seconds. |
Conditions For Setting The DTC
Rich Test:
The PCM detects that the O2S 1 parameter is more than 946 mV for 50 seconds.
OR
Decel. Fuel Cutoff Test:
The PCM detects that the O2S 1 parameter is more than 1,042 mV for 2.5 seconds.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
The diagnostic trouble code (DTC) P0132 or the rich exhaust is most likely caused by one of the following conditions:
| • | The fuel pressure--The system will go rich if the fuel pressure is too high. The PCM can compensate for some increase. However, if the fuel pressure gets too high, a DTC P0132 will set. Refer to Fuel System Diagnosis . |
| • | A leaking injector--A leaking or faulty fuel injector can cause the system to go rich causing a DTC P0132. Refer to Fuel Injector Circuit Diagnosis . |
| • | The electronic ignition (EI) shielding--An open ground circuit may result in electromagnetic interference (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. |
| • | The MAP sensor--An output that causes the PCM to sense a higher than normal manifold pressure or 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. |
| • | The TP sensor--An intermittent TP sensor output will cause the system to go rich due to a false indication of the engine accelerating. |
| • | An O2S 1 contamination--Inspect the O2S 1 for silicone contamination from fuel or use of improper RTV sealant. The O2S 1 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. |
| • | Whenever the O2S pigtail wiring, the connector or the terminal are damaged, replace the entire O2S assembly. Do not attempt to repair the wiring, the connectors or the terminals. In order for the sensor to function properly, the O2S 1 must have a clean air reference. The O2S wires obtains this clean air reference. Any attempt to repair the wires, the connectors or the terminals could result in the obstruction of the clean air reference. Any attempt to repair the wires, the connectors or the terminals could degrade the O2S performance. |
Step | Action | Values | Yes | No | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views | ||||||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||||||
2 |
Does the O2S 1 voltage measure more than the value specified? | 946 mV | Go to Step 4 | Go to Step 3 | ||||||||||
3 |
Did the DTC fail this ignition? | -- | Go to Step 4 | Go to Diagnostic Aids | ||||||||||
4 |
Does the O2S 1 voltage measure above the specified value? | 500 mV | Go to Step 6 | Go to Step 5 | ||||||||||
5 | The O2S 1 is detecting a rich exhaust condition or may be contaminated. Check for one of the following conditions:
Repair any of the above or similar engine conditions as necessary. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 7 | ||||||||||
6 | Test the high signal circuit of the O2S for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 8 | ||||||||||
7 |
Important: Before replacing a contaminated O2S 1 determine and repair the cause of the contamination. Replace the O2S 1. Refer to Oxygen Sensor Replacement . Did you complete the replacement? | -- | Go to Step 9 | -- | ||||||||||
8 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 9 | -- | ||||||||||
9 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 10 | ||||||||||
10 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||||||
