Circuit Description
The powertrain control module (PCM) supplies a voltage of about 447 mV between the heated oxygen sensor (HO2S 1) high signal and the low signal circuit. The HO2S 1 varies the voltage within a range of about 1,000 mV if the exhaust is rich, down through about 100 mV if the exhaust is lean.
The sensor is like an open circuit and produces no voltage when below 315°C (600°F).
Do not attempt to repair the HO2S. Replace the entire HO2S if the following conditions exist:
| • | Damaged wiring |
| • | Damaged electrical connector |
| • | Damaged terminals |
Conditions For Running The DTC
| • | DTCs P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0201, P0202, P0203, P0204, P0205, P0206, P0300, P0336, P0440, P0446, P0452, P0453, P0507, P0601, P0602, P0604, P0606, P1120, P1220, P1221, P1271, P1275, P1280, P1484, P1512, P1514, P1515, P1516, P1621, P1635, P1639, P1680, or P1681 are not set. |
| • | The fuel level sensor is more than 10 percent. |
| • | The ignition 1 signal is more than 10 volts. |
| • | The engine run time is more than 10 seconds. |
| • | The engine coolant temperature (ECT) is more than 70°C (158°F). |
| • | The engine is operating in Closed Loop. |
| • | The throttle position (TP) indicated angle is between 15-50 percent. |
| • | The accelerator pedal position (APP) indicated angle is more than 1.2 percent. |
| • | The manifold absolute pressure (MAP) sensor is more than 25 kPa. |
| • | The above conditions have been met for 3.8 seconds. |
Conditions For Setting The DTC
The HO2S 1 voltage is more than 946 mV for 50 seconds.
Action Taken When the DTC Sets
| • | The malfunction indicator lamp (MIL) will illuminate after two consecutive ignition cycles in which the diagnostic runs with the fault active. |
| • | The PCM will record the operating conditions at the time that the diagnostic fails. This information will store in the Freeze Frame/Failure Records buffers. |
| • | A history DTC stores. |
| • | The vehicle will operate in 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. |
| • | Use a scan tool to clear the DTCs. |
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 too high. The PCM can compensate for some increase, however, if it gets too high, a DTC P0132 will be set. |
| • | Leaking injector--A leaking or malfunctioning injector can cause the system to go rich causing a DTC P0132. Refer to Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2 . |
| • | 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. |
| • | 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. |
| • | TP sensor--An intermittent TP sensor output will cause the system to go rich due to a false indication of the engine accelerating. |
| • | HO2S 1 contamination--Inspect the HO2S 1 sensor for silicone contamination from fuel or the use of improper RTV sealant. The HO2S 1 sensor may have a white powdery coating and this will result in a high but false voltage signal, indicating a rich exhaust. 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 Connector End View Reference: Engine Controls Connector End Views | ||||||||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||||||||
2 |
Does the voltage measure above the specified value? | 946 mV | Go to Step 4 | Go to Step 3 | ||||||||||||
3 |
Does the DTC fail this ignition? | -- | Go to Step 4 | |||||||||||||
4 |
Is the HO2S voltage near the value specified? | 447 mV | Go to Step 5 | Go to Step 6 | ||||||||||||
5 | The HO2S 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 HO2S 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 9 | Go to Step 8 | ||||||||||||
7 |
Important: Before replacing a contaminated HO2S, determine and repair the cause of the contamination. Replace the HO2S. Refer to Heated Oxygen Sensor 1 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 |
Does the DTC run and pass? | -- | Go to Step 10 | Go to Step 2 | ||||||||||||
10 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |||||||||||||
