For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptors

DTC P013A: HO2S Slow Response Rich to Lean Bank 1 Sensor 2
DTC P013C: HO2S Slow Response Rich to Lean Bank 2 Sensor 2
DTC P013E: HO2S Delayed Response Rich to Lean Bank 1 Sensor 2
DTC P014A: HO2S Delayed Response Rich to Lean Bank 2 Sensor 2

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
HO2S Bank 1 Sensor 1 Signal | P0131 | P0134, P0135 | P0132 | P0133, P2096, P2097
HO2S Bank 1 Sensor 2 Signal | P0137 | P0140, P013A | P0138 | P0140, P013A, P013E
HO2S Bank 2 Sensor 1 Signal | P0151 | P0154, P0155 | P0152 | P0153, P2098, P2099
HO2S Bank 2 Sensor 2 Signal | P0157 | P0160, P013C | P0158 | P0160, P013C, P014A
HO2S Bank 1 Sensor 1 Low Reference | -- | P0134, P0135 | -- | P0133, P2096, P2097
HO2S Bank 1 Sensor 2 Low Reference | -- | P0140, P013A | -- | P0140, P013A, P013E
HO2S Bank 2 Sensor 1 Low Reference | -- | P0154, P0155 | -- | P0153, P2098, P2099
HO2S Bank 2 Sensor 2 Low Reference | -- | P0160, P013C | -- | P0160, P013C, P014A

### Circuit Description

The heated oxygen sensors (HO2S) are used for fuel control and catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the engine is started, the control module operates in an Open Loop mode, ignoring the HO2S signal voltage while calculating the air-to-fuel ratio. The control module supplies the HO2S with a reference, or bias voltage of about 450 mV. While the engine runs, the HO2S heats up and begins to generate a voltage within a range of 0-1,000 mV. This voltage will fluctuate above and below the bias voltage. Once sufficient HO2S voltage fluctuation is observed by the control module, Closed Loop is entered. The control module uses the HO2S voltage to determine the air-to-fuel ratio. An HO2S voltage that increases above bias voltage toward 1,000 mV indicates a rich fuel mixture. An HO2S voltage that decreases below bias voltage toward 0 mV indicates a lean fuel mixture.

The heating elements inside each HO2S heat the sensor to bring the sensor up to operating conditions faster. This allows the system to enter Closed Loop earlier and the control module to calculate the air-to-fuel ratio sooner.

### Conditions for Running the DTCs

• | Before the ECM can reports that DTC P013A, P013C, P013E, or P014A failed, DTCs P0030, P0031, P0032, P0050, P0051, P0052, P0135, and P0155 must run and pass.

• | DTC P0036, P0037, P0038, P056, P0057, P0058, P0137, P0138, P0140, P0141, P0157, P0158, P0160, P0161, P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0442, P0443, P0455, P0458, P0459, P2096, P2097, P2098, P2099, P2177, P2178, P2179, P2088, P2089, P2090, P2232, P2235, P2270, P2271, P2272, or P2273 is not set.

• | The ignition voltage is greater than 10 volts.

• | The HO2S 1 and 2 are in closed loop.

• | The HO2S 2 resistance is less than 900 ohms.

• | The HO2S 2 has switched from lean to rich during the ignition cycle.

• | The calculated exhaust gas mass flow rate is greater than 2.22 g/s.

• | The calculated exhaust temperature for HO2S 2 is warmer than 450°C (842°F).

• | The HO2S 1 signal voltage is less than 141 mV

• | The HO2S 2 signal voltage is greater than 590 mV at the beginning of decel fuel cut-off - DTC P013E and P014A only.

• | The DTCs run continuously once the conditions above exist.

### Conditions for Setting the DTCs

#### P013A or P013C

The ECM determines that the response time for the HO2S 2 to switch from greater than 400 mV to less than 200 mV is greater than 1 second. The condition exists for greater than 4 seconds or for a cumulative time of 30 seconds.

#### P013E or P014A

• | The ECM determines the time for the HO2S 2 to transition from greater than 590 mV to less than 140 mV, during decel fuel cut-off is greater than 4 seconds. The condition exists for greater than 4 seconds or for a cumulative time of 30 seconds.

| OR

• | The ECM determines that the air flow into the engine exceeded 15 grams before the HO2S 2 transitions to less than 140 mV, during decel fuel cut-off.

### Action Taken when the DTCs Set

DTCs P013A, P013C, P013E, and P014A are Type B DTCs.

### Conditions for Clearing the MIL/DTCs

DTCs P013A, P013C, P013E, and P014A are Type B DTCs.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. Ignition ON, observe the scan tool DTC information. Verify no other DTC is set.

⇒ | If any other DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle.

2. Engine idling, observe the appropriate scan tool HO2S voltage parameter. The voltage should fluctuate above and below the range of 401-519 mV.
3. Observe the DTC information with a scan tool. DTC P013A, P013C, P013E, and P014A should not set.
4. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the appropriate HO2S 2.
2. Ignition ON, verify that the scan tool HO2S voltage parameter is between 400-520 mV.

⇒ | If less than the specified range, test the signal circuit terminal B for a short to ground. If the circuit/connections test normal, replace the ECM.

⇒ | If greater than the specified range, test the signal circuit terminal B for a short to voltage. If the circuit/connections test normal, replace the ECM.

3. Connect a 3 A fused jumper wire between the signal circuit terminal B and ground. Verify the scan tool HO2S voltage parameter is less than 60 mV.

⇒ | If greater than the specified range, test the signal circuit for an open/high resistance. If the circuit/connections test normal, replace the ECM.

4. Connect a 3 A fused jumper wire between the signal circuit terminal B and the low reference circuit terminal A. Verify the scan tool HO2S voltage parameter is less than 60 mV.

⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance or for a short to voltage. If the circuit/connections test normal, replace the ECM.

5. Verify that none of the following conditions exist:

• | Lean or rich condition.

• | Water intrusion in the HO2S harness connector

• | HO2S wiring harness damage

• | Incorrect RTV sealant

• | Low or high fuel system pressure--Refer to Fuel System Diagnosis.

• | Fuel that is contaminated--Refer to Alcohol/Contaminants-in-Fuel Diagnosis.

• | Fuel saturation of the evaporative emission (EVAP) canister

• | Exhaust leaks near the HO2S

• | Engine vacuum leaks

• | Engine oil consumption

• | Engine coolant consumption

⇒ | If you find any of the above conditions, repair as necessary.

6. If all conditions test normal, replace the appropriate HO2S 2.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Heated Oxygen Sensor Replacement - Bank 1 Sensor 2

• | Heated Oxygen Sensor Replacement - Bank 2 Sensor 2

• | Control Module References for engine control module replacement, setup, and programming