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 provide an overview of each diagnostic category.

### DTC Descriptor

DTC P0137 00: HO2S Circuit Low Voltage Sensor 2
DTC P0138 00: HO2S Circuit High Voltage Sensor 2
DTC P0139 00: HO2S Circuit Slow Responce Sensor 2
DTC P0140 00: HO2S Circuit Insufficient Activity Sensor 2
DTC P2270 00: HO2S Signal Stuck Lean Sensor 2
DTC P2271 00: HO2S Signal Stuck Rich Sensor 2
DTC P2A01 00: HO2S Performance During Decel Fuel Cut-Off Sensor 2

### Diagnostic Fault Information

Circuit | Short to Ground | Open | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
HO2S 2 Heater Voltage Supply | Open fuse | P0141 00 | -- | P0141 00
HO2S 2 Heater Low Control | -- | P0141 00 | P0141 00 | P0141 00
HO2S 2 Signal | P0137 00 | P0140 00 | P0138 00 | P0139 00, P0140 00, P2A01 00, P2270 00, P2271 00
HO2S 2 Voltage Reference | P0137 00 | P0140 00 | -- | --

### Circuit/System Description

Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. The heated oxygen sensor (HO2S) 2 compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The heated oxygen sensor (HO2S) 2 must reach operating temperature to provide an accurate voltage signal. Heating elements inside the heated oxygen sensor (HO2S) 2 minimize the time required for the sensors to reach operating temperature. The engine control module (ECM) supplies the heated oxygen sensor (HO2S) 2 with a reference, or bias, voltage of about 450 mV. When the engine is first started, the ECM operates in open loop, ignoring the heated oxygen sensor (HO2S) 2 voltage signal. Once the heated oxygen sensor (HO2S) 2 reaches operating temperature and closed loop is achieved, the heated oxygen sensor (HO2S) 2 generates a voltage within a range of 0-1000 mV that fluctuates above and below bias voltage. High heated oxygen sensor (HO2S) 2 voltage indicates a rich exhaust stream. Low heated oxygen sensor (HO2S) 2 voltage indicates a lean exhaust stream.

### Conditions for Running the DTC

#### P0137 00

• | DTCs P0107 00, P0108 00, P0136 00, P0137 00, P0138 00, P0139 00, P0140 00, P0141 00, P0443 00, P0458 00, P0459 00, P2270 00, P2271 00, P2A01 00 are not set.

• | The engine is running.

• | The engine speed is less than 6000 RPM.

• | DTC P0137 00 runs once per drive cycle when the above conditions are met for 2 s.

#### P0138 00

• | DTCs P0136 00, P0137 00, P0138 00, P0139 00, P0140 00, P0141 00, P2270 00, P2271 00, P2A01 00 are not set.

• | The ignition is ON.

#### P0139 00

• | DTCs P000A 00, P000B 00, P0010 00, P0011 00, P0013 00, P0014 00, P0016 00, P0017 00, P0107 00, P0108 00, P0117 00, P0118 00, P0119 00, P0121 00, P0122 00, P0123 00, P0136 00, P0137 00, P0138 00, P0141 00, P0171 00, P0172 00, P0201 00, P0202 00, P0203 00, P0204 00, P0221 00, P0222 00, P0223 00, P0261 00, P0262 00, P0264 00, P0265 00, P0267 00, P0268 00, P0270 00, P0271 00, P0300 00, P030 001, P0302 00, P0303 00, P0304 00, P0313 00, P0335 00, P0336 00, P0340 00, P0341 00, P0365 00, P0366 00, P0443 00, P0458 00, P0459 00, P0496 00, P0501 00, P2088 00, P2089 00, P2090 00, P2091 00, P2100 00, P2101 00, P2176 00, P2270 00, P2271 00, P2A01 00 are not set.

• | The ignition is ON.

• | The engine coolant is hotter than 60°C (140°F).

• | The heated oxygen sensor (HO2S) 2 signal voltage is more than 552 mV.

• | The vehicle speed is between 19-31 km/h (12-93 mph).

• | DTC P0140 00 runs continuously when the above conditions are met for 60 min.

#### P0140 00

• | DTCs P000A 00, P000B 00, P0010 00, P0011 00, P0013 00, P0014 00, P0016 00, P0017 00, P0030 00, P0031 00, P0032 00, P0107 00, P0108 00, P0117 00, P0118 00, P0119 00, P0121 00, P0122 00, P0123 00, P0130 00, P0131 00, P0132 00, P0133 00, P0137 00, P0138 00, P0139 00, P0141 00, P0171 00, P0172 00, P0221 00, P0222 00, P0223 00, P0300 00, P0301 00, P0302 00, P0303 00, P0304 00, P0313 00, P0335 00, P0336 00, P0340 00, P0341 00, P0365 00, P0366 00, P0443 00, P0458 00, P0459 00, P0496 00, P2088 00, P2089 00, P2090 00, P2091 00, P2176 00, P2270 00, P2271 00, P2297 00, P2A01 00 are not set.

• | The engine has been running for more than 5 min.

• | The engine coolant is greater than 75°C (167°F).

• | The engine run time parameter is less than 90 s.

#### P2270 00

• | DTCs P0137 00, P0138 00 00, P0140 00, P0141 00, P0443 00, P0458 00, P0459 00, are not set.

• | The engine is running.

• | The ignition voltage is more than 10.5 V.

• | The heated oxygen sensor (HO2S) 2 has been in closed loop for more than 10 s.

• | The decel fuel cut-off (DFCO) is inactive.

• | DTC P2270 00 runs continuously when the above conditions are met for 10 min.

#### P2271 00

• | DTCs P000A 00, P000B 00, P0010 00, P0011 00, P0013 00, P0014 00, P0016 00, P0017 00, P0030 00, P0031 00, P0032 00, P0107 00, P0108 00, P0117 00, P0118 00, P0119 00, P0121 00, P0122 00, P0123 00, P0130 00, P0131 00, P0132 00, P0133 00, P0137 00, P0138 00, P0139 00, P0141 00, P0171 00, P0172 00, P0221 00, P0222 00, P0223 00, P0300 00, P0301 00, P0302 00, P0303 00, P0304 00, P0313 00, P0335 00, P0336 00, P0340 00, P0341 00, P0365 00, P0366 00, P0443 00, P0458 00, P0459 00, P0496 00, P2088 00, P2089 00, P2090 00, P2091 00, P2176 00, P2270 00, P2271 00, P2297 00, P2A01 00 are not set.

• | The engine has been running for more than 5 min.

• | The engine coolant is hotter than 75°C (167°F).

• | DTC P2271 00 runs continuously when the above conditions are met for 10 min.

#### P2A01 00

• | DTCs P0107 00, P0108 00, P0136 00, P0137 00, P0138 00, P0139 00, P0140 00, P0141 00, P0171 00, P0172 00, P0201 00, P0202 00, P0203 00 P0204 00, P0261 00, P0262 00, P0264 00, P0265 00, P0267 00, P0268 00, P0270 00, P0271 00, P0300 00, P0301 00, P0302 00, P0303 00, P0304 00, P0313 00, P0443 00, P0458 00, P0459 00, P0496 00, P2270 00, P2271 00 are not set.

• | The ignition is ON.

• | the decel fuel cut-off (DFCO) is active.

• | DTC P2A01 00 runs continuously when the above conditions are met.

### Conditions for Setting the DTC

#### P0137 00

• | The ECM detects that the heated oxygen sensor (HO2S) 2 voltage parameter is less than 24 mV.

• | DTC P0137 00 sets within 0.1 s during the lean test when the above condition is met.

#### P0138 00

• | The ECM detects that the heated oxygen sensor (HO2S) 2 voltage is more than 1.2 V.

• | DTC P0138 00 sets when the above condition is met.

#### P0139 00

• | The ECM detects that the heated oxygen sensor (HO2S) 2 has switched less than a calibrated number of times within a calibrated time period that depends on driving conditions.

• | DTC P0139 00 sets within 4 s when the above condition is met.

#### P0140 00

• | The ECM detects that the heated oxygen sensor (HO2S) 2 voltage parameter is between 0.298-0.605 V.

• | DTC P0140 00 sets within 4 s when the above condition is met for 60 s.

#### P2270 00

• | The ECM detects that the heated oxygen sensor (HO2S) 2 voltage oscillations are slower than a calibrated value.

• | DTC P2270 sets within 4 s when the above condition is met continuously, or within 50 s when the above condition is met cumulatively.

#### P2271 00

• | The ECM detects that the HO2S 2 voltage oscillations are faster than a calibrated value.

• | DTC P2271 00 sets within 4 s when the above condition is met continuously, or within 50 s when the above condition is met cumulatively.

#### P2A01 00

• | The ECM detects that the heated oxygen sensor (HO2S) 2 voltage is more than 0.151 V.

• | DTC P2A01 00 sets when the above condition is met.

### Action Taken When the DTC Sets

DTCs P0137 00, P0138 00, P0139 00, P0140 00, P2270 00, P2271 00, and P2A01 00 are Type B DTCs.

### Conditions for Clearing the DTC

DTCs P013 007, P0138 00, P0139 00, P0140 00, P2270 00, P2271 00, and P2A01 00 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

• | Heated Oxygen Sensor 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. Clear the DTCs with a scan tool.
2. Operate the vehicle within the conditions for running and setting the DTC. The DTC should not set.

### Circuit/System Testing

Note: You must perform the circuit/system verification before proceeding with circuit/system testing.

1. Ignition OFF, disconnect the harness connector at the B52B Heated Oxygen Sensor (HO2S).
2. Ignition OFF, measure for less than 5 Ω between the B52B Heated Oxygen Sensor (HO2S) low signal circuit terminal 4 and ground.

⇒ | If more than the specified range, test the appropriate HO2S low signal circuit for an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

3. Ignition ON, verify the appropriate scan tool HO2S parameter is approximately 450 mV.

⇒ | If more than the specified value, test the appropriate B52B Heated Oxygen Sensor (HO2S) high signal circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

⇒ | If less than the specified value, test the appropriate B52B Heated Oxygen Sensor (HO2S) high signal circuit for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

4. Ignition ON, install a 3A fused jumper wire at the B52B Heated Oxygen Sensor (HO2S) high signal circuit terminal 2. Toggle the jumper wire between the B52B Heated Oxygen Sensor (HO2S) low signal circuit terminal 4 and battery voltage. Verify the appropriate scan tool HO2S 2 parameter toggles between 0 mV and approximately 1000 mV.

⇒ | If the appropriate scan tool B52B Heated Oxygen Sensor (HO2S) parameter does not toggle correctly, test the B52B Heated Oxygen Sensor (HO2S) high signal circuit for an open/high resistance. If the circuits test normal, replace the K20 Engine Control Module (ECM).

5. If all circuits test normal, replace the appropriate B52B Heated Oxygen Sensor (HO2S).

### Repair Instructions

Caution: Refer to Heated Oxygen Sensor Resistance Learn Reset Caution in the Preface section.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Heated Oxygen Sensor 2 Replacement

• | Control Module References for ECM replacement, setup, and programming