Circuit Description
The Powertrain Control Module (PCM) supplies a voltage of about 0.45 volts to the Oxygen Sensor 1 (O2S 1). The O2S 1 varies the voltage between a range of about 1 volt if the exhaust is rich, down through about 0.10 volt if the exhaust is lean.
The O2S 1 is like an open circuit and produces no voltage when the O2S 1 temperature is below 315°C (600°F). An open O2S 1 circuit or cold sensor causes an Open Loop operation.
Conditions For Setting The DTC
| • | DTCs P0106, P0107, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0200, P0300, P0301, P0302, P0303, P0304, P0404, P0405, P0506, P0507, P1404, P1441 not set. |
| • | Engine run time is greater than 25 seconds. |
| • | Engine Coolant Temperature (ECT) is greater than 70°C (158°F). |
| • | Air/fuel ratio is between 14.5:1 and 14.7:1. |
| • | Engine is operating in Closed Loop. |
| • | Throttle Position (TP) angle is between 5% and 50%. |
| • | Engine has met the above conditions for 30 seconds. |
| • | O2S 1 voltage is greater than 945 mV for 50 seconds. |
| Or |
| • | O2S 1 voltage is greater than 1042 mV for 50 seconds while in deceleration mode. |
Action Taken When the DTC Sets
| • | The malfunction indicator lamp (MIL) will illuminate. |
| • | The PCM will record the operating conditions at the time that the diagnostic fails. The Freeze Frame and Failure Records buffers will store this information. |
| • | A history DTC stores. |
Conditions for Clearing the MIL/DTC
| • | The malfunction indicator lamp (MIL) will turn OFF after 3 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 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. See Fuel System Diagnosis . |
| • | A leaking injector - A leaking or faulty fuel injector can cause the system to go rich causing a DTC P0132. See Injector Coil Test Procedure. Refer to the Fuel Injector Balance Test and Fuel Injector Solenoid Coil Test (ECT Within 10C-35C (50F-95F). |
| • | The Electronic Ignition (EI) shielding - An Open ground circuit 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. |
| • | The 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. |
| • | A pressure regulator - Check for a leaking fuel pressure regulator diaphragm by checking for the presence of liquid fuel in the vacuum line to the regulator. |
| • | 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 a 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 oxygen sensor pigtail wiring, the connector, or the terminal are damaged, replace the entire oxygen sensor 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 oxygen sensor 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 oxygen sensor's performance. |
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
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The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored in the scan tool for later reference.
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This step determines if DTC P0132 is the result of a hard failure or an intermittent condition. It may be necessary to operate the vehicle within the Freeze Frame conditions and Conditions for Setting the DTC in order to duplicate the malfunction detected by the PCM.
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This step simulates a DTC P0131. If the PCM senses the change, the PCM and wiring are OK.
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Replacement PCMs must be reprogrammed and the crankshaft position system variation procedure must be preformed. Refer to the latest Isuzu Technical Communication System (ITCS) information for programming procedures and also refer to the Powertrain Control Module (PCM) .
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If no malfunctions have been found at this point and no additional DTCs were set, refer to Diagnostic Aids for additional checks and information.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to | ||
Does the O2S 1 voltage remain above the specified value? | 1042 mV | |||
3 |
Does the O2S 1 voltage stay above the specified value? | 1042 mV | ||
Does the DVM indicate the O2S 1 voltage below the specified value? | 600 mV (0.6V) | Go to Diagnostic Aids | ||
5 | Check the O2S 1 sensor signal circuit for a short to voltage and repair as necessary. Was a repair necessary? | -- | ||
Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | ||
7 |
Does the scan tool indicate that this diagnostic ran and passed? | -- | ||
Check if any additional DTCs are set. Are any DTCs displayed that have not been diagnosed? | -- | Go to applicable DTC table | System OK Refer to Diagnostic Aids |
