Circuit Description
The powertrain control module (PCM) supplies a voltage of approximately 0.45 volt between the oxygen sensor (O2S) high signal and the low signal circuit. The O2S varies the voltage within a range of approximately 1 volt if the exhaust is rich, to approximately 0.10 volt if the exhaust is lean.
The sensor is like an open circuit and does not produce any voltage if the temperature is less than 315°C (600°F). An open sensor circuit or a cold sensor causes an open loop operation.
Conditions For Running The DTC
| • | DTCs P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0171, P0201-P0204, P0300, P0301-P0304, P0335, P0440, P0442, P0446, P0506, P0507, P0601, P0602, or P1441 are not set. |
| • | The coolant temperature is greater than 70°C (158°F). |
| • | The battery voltage is greater than 10 volts. |
| • | The fuel level is greater than 10 percent. |
| • | The engine run time is greater than 10 seconds. |
| • | The engine is operating in Closed Loop. |
| • | The throttle position (TP) angle is between 8-50 percent. |
| • | The manifold absolute pressure (MAP) is greater than 25 kPa. |
| • | The engine has met the above conditions for 4 seconds. |
Conditions For Setting The DTC
| • | O2S voltage is more than 946 mV for 50 seconds. |
| Or |
| • | O2S voltage is more than 1,042 mV for 2.5 seconds while in deceleration mode. |
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
DTC P0132 or rich exhaust is most likely caused by one of the following items:
| • | The fuel pressure--The system will go rich if fuel pressure is too high. The PCM can compensate for some increase, but if the fuel pressure becomes too high, DTC P0132 will be set. Refer to the Fuel System Diagnosis . |
| • | A leaking injector--A leaking or malfunctioning injector can cause the system to go rich causing DTC P0132. Refer to the Fuel Injector Solenoid Coil Test . |
| • | The electronic ignition (EI) shielding--An open ignition control module (ICM) reference low circuit may result in electromagnetic interference (EMI) or induced electrical noise. The PCM senses this noise as a 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 to diagnose this problem. |
| • | The manifold absolute pressure (MAP) sensor--An output that causes the PCM to sense a higher than normal manifold pressure, or a low vacuum, can cause the system to go rich. Disconnecting the MAP sensor electrical connector 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 MAP sensor is disconnected. |
| • | The pressure regulator--Check for a leaking fuel pressure regulator diaphragm by checking for the presence of liquid fuel in the vacuum line to the fuel pressure regulator. |
| • | The throttle position (TP) sensor--An intermittent TP sensor output will cause the system to go rich due to a false indication of the engine accelerating. |
| • | O2S contamination--Inspect the O2S sensor for silicone contamination from fuel or the use of improper room-temperature vulcanizing (RTV) sealant. The O2S sensor may have a white powdery coating and this will result in a high but false voltage signal, an indication of a rich exhaust. The PCM will then reduce the amount of fuel delivered to the engine, causing a severe surge or driveability problem. |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Values | Yes | No | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||||||||
Does the O2S voltage measure more than the value specified? | 976 mV | Go to Step 4 | Go to Step 3 | |||||||||||||
3 | This DTC is intermittent. Are any additional DTCs stored? | -- | Go to Diagnostic Aids | |||||||||||||
4 |
Does the voltage measure within the specified value? | 351-551 mV | Go to Step 5 | Go to Step 6 | ||||||||||||
5 | The O2S 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 10 | Go to Step 7 | ||||||||||||
6 | Test the O2S high signal circuit for a short to voltage. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 9 | ||||||||||||
7 | Inspect for poor connections at the harness connector of the O2S sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 8 | ||||||||||||
8 |
Important: Before replacing a contaminated O2S determine and repair the cause of the contamination. Replace the O2S. Refer to Oxygen Sensor Replacement . Did you complete the replacement? | -- | Go to Step 10 | -- | ||||||||||||
9 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 10 | -- | ||||||||||||
10 |
Does the DTC run and pass? | -- | Go to Step 11 | Go to Step 2 | ||||||||||||
11 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |||||||||||||
