Circuit Description
The PCM supplies a bias voltage of about 450 mV between the HO2S signal and low circuits. When measured with a 10 megohm digital voltmeter, this may display as low as 320 mV. The oxygen sensor varies the voltage within a range of about 1000 mV when the exhaust is rich, down through about 10 mV when exhaust is lean. The PCM constantly monitors the HO2S signal during closed loop operation and compensates for a rich or lean condition by decreasing or increasing injector pulse width as necessary. If the Bank 1 HO2S 1 voltage remains excessively high for an extended period of time, DTC P0132 will be set.
Conditions for Running the DTC
| • | No Misfire, CKP, Fuel Injector, MAF, TP, EVAP, IAT, MAP, Fuel Trim, EGR or ECT DTCs are present. |
| • | The vehicle is in closed loop. |
| • | The Air/Fuel Ratio is greater than or equal to 14.5 but less than or equal to 14.8 |
| • | Throttle angle is between 3% and 40% |
Conditions for Setting the DTC
| • | Bank 1 HO2S 1 signal voltage remains above 975 mV during normal closed loop operation |
| OR |
| • | Bank 1 HO2S 1 signal voltage remains above 200 mV during decel fuel cutoff. |
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed. |
| • | The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed. |
| • | The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using the scan tool. |
Diagnostic Aids
Check the following items:
| • | High fuel pressure -- The system will go rich if pressure is too high. The PCM can compensate for some increase. However, if fuel pressure is too high, a DTC P0132 may be set. Refer to Fuel System Pressure Test . |
| • | Fuel injector(s) contaminated or faulty -- Refer to Fuel Injector Balance Test . |
| • | Check the EVAP Canister for Fuel Saturation. If the EVAP Canister is full of fuel, check canister control and hoses. Refer to Evaporative Emission Control System Diagnosis . |
| • | Disconnect the MAF sensor and see if the rich condition is corrected. If so, replace the MAF sensor. |
| • | Check for a leaking fuel pressure regulator diaphragm by checking the vacuum line to the fuel pressure regulator for the presence of fuel. |
| • | An intermittent TP sensor output will cause the system to go rich due to a false indication of the engine accelerating. |
| • | Shorted HO2S -- If the HO2S is internally shorted the HO2S voltage displayed on the scan tool will be over 1 volt. Disconnect the affected HO2S and jumper the HO2S low circuit to ground with the key ON. If the displayed HO2S voltage changes from over 1000 mV to around 450 mV, replace the HO2S. Silicon contamination of the HO2S can also cause a high HO2S voltage to be indicated. This condition is indicated by a powdery white deposit on the portion of the HO2S exposed to the exhaust stream. If contamination is noticed , replace the affected HO2S. |
| • | Open HO2S Signal or Low Circuit or Faulty HO2S -- A poor connection or open in the HO2S signal or low circuit can cause the DTC to set during deceleration fuel mode. An HO2S which is faulty and not allowing a full voltage swing between the rich and lean thresholds can also cause this condition. Operate the vehicle while monitoring the HO2S voltage with a scan tool. If the HO2S voltage is limited within a range between 300mV to 600mV, check the HO2S signal and low circuit wiring and associated terminal connections. If the wiring and connections are OK, replace the HO2S. |
| • | Poor connection at the PCM - Inspect harness connectors for the following conditions: |
| - | Backed out terminals. |
| - | Improper mating. |
| - | Broken locks. |
| - | Improperly formed or damaged terminals. |
| - | Poor terminal to wire connection. |
Test Description
Number(s) below refer to step numbers on the Diagnostic Table:
-
This DTC failing during deceleration fuel mode operation (vehicle speed above 25 mph, TP angle below 3%) may indicate a condition described in Diagnostic Aids. If this DTC test passes while the Fail Records conditions are being duplicated, an intermittent condition is indicated. Review the Fail Records vehicle mileage since the diagnostic test last failed. This may help determine how often the condition that caused the DTC to be set occurs.
-
This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is replaced, the new PCM must be programmed.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
2 |
Does the scan tool indicate HO2S voltage more than the specified value? | 800 mV | ||
Operate vehicle in Decel fuel mode (vehicle speed above 25 mph, TP angle below 3%) while observing HO2S voltage parameter on the scan tool. Does the HO2S voltage remain above the specified value while in Decel fuel mode? | 110 mV | |||
4 |
Does the scan tool indicate this DTC failed this ignition? | -- | Go to Diagnostic Aids | |
5 | Disconnect the HO2S and jumper low circuit to ground. Does scan tool indicate HO2S voltage near the specified value? | 450 mV | Go to Diagnostic Aids | |
6 |
Does the voltage measure more than specified value? | 600 mV | ||
7 | Repair the short to voltage in the HO2S signal circuit. Refer to Wiring Repairs . Did you complete the repair? | -- | -- | |
|
Important: Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Did you complete the replacement? | -- | -- | ||
9 |
Does the DTC reset? | -- | System OK |
