Circuit Description
The powertrain control module (PCM) supplies a voltage of 0.45 volt between terminals J1-13 and J1-14. If measured with a 10 megohm digital voltmeter, this may read as low as 0.32 volt. The oxygen sensor (O2S) 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 it is below 315°C (600°F). An open sensor circuit or a cold sensor causes Open Loop operation.
If the oxygen sensor pigtail wiring, connector, or terminal are damaged, the entire O2S assembly must be replaced. DO NOT attempt to repair the wiring, connector, or terminals. In order for the sensor to function properly, it must have a clean air reference provided to it. This clean air reference is obtained by way of the O2S wires. Any attempt to repair the wires, connectors, or terminals could result in the obstruction of the air reference and degrade O2S performance. Refer to Section 8A-5, Heated Oxygen Repair.
Conditions for Setting
| • | When one or more of the following DTCs P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0200, P0300, P0301, P0302, P0303, P0304, P0441, P0562, P563, P1171, P1441 are not present. |
| • | The engine has been running for at least 10 seconds. |
| • | Engine coolant temperature is greater than 50°C (122°F). |
| • | TP angle is between 25-50 percent. |
| • | Air/Fuel ratio is between 14.5-14.7. |
| • | The engine is operating in Closed Loop. |
| • | The engine has met the TP sensor, Air/Fuel ratio, Closed Loop, and engine coolant temperature conditions for 10 seconds. |
| • | The O2S voltage is greater than 752 mV. |
| • | The above conditions are present for at least 30 seconds. |
Action Taken
| • | Malfunction indicator lamp (MIL) illuminates after one driving cycle with the fault active. |
| • | Vehicle will operate in Open Loop. |
Conditions for Clearing the MIL/DTC
| • | The MIL will turn OFF after passing three consecutive diagnostic tests. |
| • | A history DTC will clear after 40 consecutive ignition cycles have occurred without a fault. |
| • | History and current DTCs can be cleared by using a scan tool. |
Diagnostic Aids
The DTC P0132 or rich exhaust is most likely caused by one of the following:
| • | Fuel pressure--The system will go rich if pressure is too high. The PCM can compensate for some increase, however, if it gets too high a DTC P0132 will be set. Refer to Fuel System Diagnosis . |
| • | Leaking injector--A leaking or faulty injector can cause the system to go rich causing a DTC P0132. Refer to Injector Coil Test Procedure, Chart C-2A. |
| • | 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--Inspect 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 contamination--Inspect the O2S 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, a rich exhaust indication. The PCM will then reduce the amount of fuel delivered to the engine causing a severe surge or driveability problem. |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Was the On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | |
2 |
Does the O2S 1 voltage remain above the specified value? | 752 mV | Go to Step 4 | Go to Step 3 |
3 |
Does O2S 1 voltage stay above the specified value? | 752 mV | Go to Diagnostic Aids | Go to Step 10 |
4 | Disconnect the O2S 1. Does the scan tool indicate O2S 1 voltage within the specified range? | 407-509 mV | Go to Diagnostic Aids | Go to Step 5 |
5 |
Does the DVM indicate a voltage above the specified value? | 500 mV | Go to Step 6 | Go to Step 7 |
6 | Repair the short to voltage in the O2S 1 signal circuit. Is the action complete? | -- | -- | |
7 | Visually and physically inspect the O2S 1 signal circuit for being shorted to battery voltage. Is the O2S 1 signal circuit shorted to battery voltage? | -- | Go to Step 8 | Go to Step 9 |
8 | Repair the O2S 1 signal circuit. Is the action complete? | -- | -- | |
9 | Replace the PCM. Is the action complete? | -- | -- | |
10 | Check the PCM for other DTCs. Are any other DTCs present? | -- | Go to applicable DTC chart | Go to Diagnostic Aids |
