This diagnostic applies only to vehicles built with case grounded heated oxygen sensors (HO2S). To identify the HO2S, refer to Engine Controls Component Views .
The powertrain control module (PCM) supplies a voltage of about 450 mV between the HO2S high and low signal circuits. The HO2S varies the voltage over a range from about 1,000 mV when the exhaust is rich, down through about 10 mV when the exhaust is lean.
The PCM monitors and stores the HO2S voltage information. The PCM evaluates the HO2S voltage samples in order to determine the amount of time the HO2S voltage was out of range. The PCM compares the stored HO2S voltage samples taken within each sample period and determines if the majority of the samples are out of the operating range.
The PCM monitors the HO2S voltage for being fixed above a predetermined voltage. If the PCM detects the voltage is above a predetermined voltage, a diagnostic trouble code (DTC) sets.
• | DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0200, P0300, P0401, P0404, P0405, P0440, P0442, P0446, P0452, P0453, P1120, P1125, P1220, P1221, P1258, P1404, P1441, P1514, P1515, P1516, P1517, or P1518 are not set. |
• | The vehicle is operating in Closed Loop. |
• | The ignition 1 signal is between 9-18 volts. |
• | The fuel tank level remaining is more than 10 percent. |
• | Intrusive tests are not in progress. |
• | The scan tool output controls are not active. |
• | The air fuel ratio is between 14.5:1-14.7:1. |
• | For vehicles with throttle-actuated control (TAC), the throttle position (TP) indicated angle is between 3-70 percent more than the value observed at idle. |
• | For vehicles without TAC, the TP is between 3-70 percent. |
• | Decel fuel cut-off (DFCO) is active. |
• | The above condition is met for 1 second. |
The HO2S voltage is more than 775 mV for 165 seconds.
The HO2S voltage is more than 540 mV for 5 seconds.
• | 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. |
• | The control module commands Open Loop. |
• | 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. |
Important: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing or replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.
• | Inspect the HO2S wire. The sensor pigtail may be in contact with the exhaust manifold or the exhaust system. |
• | Inspect the HO2S oxygen supply. An oxygen supply inside the HO2S is necessary for proper operation. The HO2S wires provides the supply of oxygen. Inspect the HO2S wires and connections for breaks or contamination. Refer to Heated Oxygen Sensor Wiring Repairs in Wiring Systems. |
• | Inspect for intermittent ground in the signal wire between the connector and the sensor. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
• | Inspect the fuel injectors. Perform the Fuel Injector Balance Test. Refer to Fuel Injector Balance Test with Tech 2 or to Fuel Injector Balance Test with Special Tool . |
For an intermittent condition, refer to Intermittent Conditions .
The numbers below refer to the step numbers on the diagnostic table.
If the voltage is above the specified value the condition is present.
Jumpering the HO2S low signal circuit to ground is necessary for the PCM to correctly measure the voltage on the HO2S high signal circuit. If the HO2S voltage is within the specified range, the PCM and HO2S high signal circuit are OK.
Step | Action | Value(s) | Yes | No | ||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Important: This diagnostic applies only to vehicles built with case grounded HO2S. To identify the HO2S, refer to Engine Controls Component Views . Schematic Reference: Engine Controls Schematics | ||||||||||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||||||||||
Is the HO2S voltage more than the specified value? | 775 mV | Go to Step 4 | Go to Step 3 | |||||||||||||||
3 |
Does the DTC fail this ignition? | -- | Go to Step 4 | Go to Diagnostic Aids | ||||||||||||||
Is the HO2S voltage within the specified range? | 350-550 mV | Go to Step 5 | Go to Step 6 | |||||||||||||||
5 |
Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 7 | ||||||||||||||
6 |
Important: The sensor may be damaged if the circuit is shorted to a voltage source. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 8 | ||||||||||||||
7 | Inspect for poor connections at the harness connector of the HO2S. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 9 | ||||||||||||||
8 | Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 10 | ||||||||||||||
9 | Replace the affected HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 or Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 . Did you complete the replacement? | -- | Go to Step 11 | -- | ||||||||||||||
10 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- | ||||||||||||||
11 |
Does the DTC run and pass? | -- | Go to Step 12 | Go to Step 2 | ||||||||||||||
12 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK |
This diagnostic applies only to vehicles built with isolated grounded heated oxygen sensors (HO2S). To identify the HO2S, refer to Engine Controls Component Views .
The powertrain control module (PCM) supplies a voltage of about 450 mV between the HO2S high and low signal circuits. The HO2S varies the voltage over a range from about 1,000 mV when the exhaust is rich, down through about 10 mV when the exhaust is lean.
The PCM monitors and stores the HO2S voltage information. The PCM evaluates the HO2S voltage samples in order to determine the amount of time the HO2S voltage was out of range. The PCM compares the stored HO2S voltage samples taken within each sample period and determines if the majority of the samples are out of the operating range.
The PCM monitors the HO2S voltage for being fixed above a predetermined voltage. If the PCM detects the voltage is above a predetermined voltage, a diagnostic trouble code (DTC) sets.
• | DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0200, P0300, P0401, P0404, P0405, P0440, P0442, P0446, P0452, P0453, P1120, P1125, P1220, P1221, P1258, P1404, P1441, P1514, P1515, P1516, P1517, or P1518 are not set. |
• | The vehicle is operating in Closed Loop. |
• | The ignition 1 signal is between 9-18 volts. |
• | The fuel tank level remaining is more than 10 percent. |
• | The fuel alcohol content is less than 90 percent. |
• | Intrusive tests are not in progress. |
• | The scan tool output controls are not active. |
• | The air fuel ratio is between 14.5:1-14.7:1. |
• | For vehicles with throttle-actuated control (TAC), the throttle position (TP) indicated angle is between 3-70 percent more than the value observed at idle. |
• | For vehicles without TAC, the TP is between 3-70 percent. |
• | Decel fuel cut-off (DFCO) is active. |
• | The above condition is met for 1 second. |
The HO2S voltage is more than 775 mV for 165 seconds.
The HO2S voltage is more than 540 mV for 5 seconds.
• | 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. |
• | The control module commands Open Loop. |
• | 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. |
Important: Never solder the HO2S wires. For proper wire and connector repair, refer to Wiring Repairs or Connector Repairs in Wiring Systems.
Inspect the following items:
• | Inspect the fuel pressure. If the pressure is too high, the system will run rich. The PCM can compensate for some increase but if the pressure becomes too high, this DTC may set. Refer to Fuel System Diagnosis . |
• | Inspect for rich fuel injectors. Perform the Fuel Injector Balance Test. Refer to Fuel Injector Balance Test with Tech 2 . |
• | Inspect for a leaking fuel injector. Refer to Fuel System Diagnosis . |
• | Inspect for fuel contamination of the engine oil |
• | Inspect the evaporative emission (EVAP) canister purge. Check for fuel saturation. If full of fuel, check the canister control and the hoses. Refer to Evaporative Emission Control System Description . |
• | Inspect for a leaking fuel pressure regulator diaphragm by checking the vacuum line to the regulator for fuel |
• | Inspect the TP sensor. An intermittent TP sensor output causes the system to run rich due to a false indication of the throttle moving. |
• | Inspect for a false rich indication due to silicon contamination of the HO2S. This DTC, accompanied by a lean driveability condition and a powdery white deposit on the sensor, may indicate a false rich condition. |
An intermittent may be caused by any of the following conditions:
• | A poor connection |
• | Rubbed through wire insulation |
• | A broken wire inside the insulation |
Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
If a repair is necessary, then refer to Wiring Repairs or Connector Repairs in Wiring Systems.
The numbers below refer to the step numbers on the diagnostic table.
Monitor the HO2S voltage of the opposite bank sensor. If the voltage activity of the opposite bank sensor is similar to the voltage activity of the suspect sensor, check for rich conditions that would affect both cylinder banks. An opposite bank sensor with normal HO2S voltage activity indicates the suspect HO2S is defective or a rich condition exists only on the suspect HO2S cylinder bank.
An HO2S contaminated by silicon will have a white, powdery deposit on the portion of the HO2S that is exposed to the exhaust stream. The usual cause of silica contamination is the use of unapproved silicon RTV engine gasket material or the use of silicon based sprays or fluids within the engine. If the cause of this contamination is not corrected, the replacement HO2S will also get contaminated.
Step | Action | Values | Yes | No | ||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Important: This diagnostic applies only to vehicles built with isolated grounded HO2S. To identify the HO2S, refer to Engine Controls Component Views . Schematic Reference: Engine Controls Schematics | ||||||||||||||||||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||||||||||||||||||
2 |
Is the HO2S voltage fixed at more than the specified value? | 775 mV | Go to Step 4 | Go to Step 3 | ||||||||||||||||||||||
3 |
Did you find and correct the condition? | -- | Go to Step 10 | Go to Diagnostic Aids | ||||||||||||||||||||||
4 |
Is the HO2S voltage within the specified range? | 351-551 mV | Go to Step 5 | Go to Step 6 | ||||||||||||||||||||||
Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 8 | |||||||||||||||||||||||
6 |
Is the voltage more than the specified value? | 20 mV | Go to Step 7 | Go to Step 9 | ||||||||||||||||||||||
7 |
Important: The sensor may be damaged if the circuit is shorted to a voltage source. Repair the short to voltage in the HO2S high signal circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 10 | -- | ||||||||||||||||||||||
Important: Before replacing a contaminated HO2S, determine and repair the cause of the contamination. Replace the affected HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 or to Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 . 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 |