Emissions Codes

Evaporative Emission Control System Malfunction

General fault in the EVAP (fuel vapor) system. The system prevents fuel vapors from escaping to atmosphere.

Evaporative Emission Control System Purge Control Valve Circuit

Fault in the EVAP purge control valve circuit.

Evaporative Emission Purge Control Valve Circuit Open

Open circuit in EVAP purge valve control circuit.

Evaporative Emission Purge Control Valve Circuit Shorted

Short circuit in EVAP purge valve control circuit.

O2 Sensor Heater Circuit Bank 2 Sensor 2

Heater circuit fault in downstream O2 sensor bank 2.

O2 Sensor Circuit Bank 2 Sensor 2

Circuit fault in the downstream O2 sensor on bank 2.

O2 Sensor Circuit Low Voltage Bank 2 Sensor 2

Downstream O2 sensor on bank 2 reads consistently low voltage.

O2 Sensor Circuit High Voltage Bank 2 Sensor 2

Downstream O2 sensor bank 2 reads consistently high voltage.

Evaporative Emission Control System Vent Control Circuit Open

Open circuit in the EVAP vent control valve circuit.

Evaporative Emission Control System Vent Control Circuit Shorted

Short circuit in the EVAP vent control valve circuit.

Secondary Air Injection System

Fault in the secondary air injection (SAI) system. The SAI pumps fresh air into the exhaust during cold starts to reduce emissions and help the catalytic converter warm up faster.

O2 Sensor Circuit High Voltage Bank 1 Sensor 3

Third O2 sensor on bank 1 reads high voltage. Some vehicles have a third O2 sensor after a secondary catalytic converter.

O2 Sensor Circuit Malfunction Bank 1 Sensor 3

The third oxygen sensor position on Bank 1 (found on some V6/V8 engines with dual catalysts) has a circuit fault.

O2 Sensor Circuit Low Voltage Bank 1 Sensor 3

The Bank 1 Sensor 3 oxygen sensor is reading consistently low voltage (lean).

O2 Sensor Circuit Slow Response Bank 1 Sensor 3

The Bank 1 Sensor 3 oxygen sensor is switching between rich and lean too slowly.

O2 Sensor Circuit No Activity Detected Bank 1 Sensor 3

The Bank 1 Sensor 3 oxygen sensor shows no voltage activity/switching at all.

O2 Sensor Heater Circuit Malfunction Bank 1 Sensor 3

The heater element inside the Bank 1 Sensor 3 oxygen sensor has failed.

O2 Sensor Circuit No Activity Detected Bank 2 Sensor 2

The downstream oxygen sensor on Bank 2 shows no voltage activity.

Secondary Air Injection System Switching Valve A Circuit Malfunction

The secondary air injection switching valve, which directs air into the exhaust during cold start to reduce emissions, has a circuit fault.

Evaporative Emission Control System Vent Valve/Solenoid Circuit Malfunction

The EVAP vent valve/solenoid circuit, which controls fresh air venting into the charcoal canister system, has an electrical fault.

Evaporative Emission Control System Pressure Sensor Malfunction

The EVAP system pressure sensor, which monitors fuel tank vapor pressure, has a fault.

Evaporative Emission Control System Pressure Sensor Range/Performance

The EVAP pressure sensor reading is out of the expected range.

Secondary Air Injection System Insufficient Flow Bank 2

Insufficient air flow has been detected in the Bank 2 secondary air injection system.

Evaporative Emission Control System Small Leak Detected

A small leak has been detected in the EVAP system. The most common cause is a loose fuel cap.

Evaporative Emission Control System Large Leak Detected

A large leak has been detected in the EVAP system.

Evaporative Emission Control System Very Small Leak

A very small leak in the EVAP system — harder to find than P0442.

O2 Sensor Heater Circuit Malfunction Bank 1 Sensor 1

The heater element inside the upstream O2 sensor has failed. The heater warms the sensor quickly at cold start.

O2 Sensor Heater Circuit Malfunction Bank 1 Sensor 2

Heater circuit fault in downstream O2 sensor Bank 1.

O2 Sensor Circuit Malfunction Bank 1 Sensor 2

Downstream O2 sensor (after catalytic converter) on Bank 1 has a circuit fault.

Secondary Air Injection System Incorrect Flow

The secondary air injection system is not delivering the expected air flow. The pump may be running but air is not reaching the exhaust.

Evaporative Emission Control System Vent Control Circuit

Fault in the EVAP vent valve circuit.

Fuel Tank Pressure Sensor Circuit Low Input

The ECM has detected an unusually low voltage signal from the Fuel Tank Pressure (FTP) sensor, which monitors pressure inside the fuel tank as part of the EVAP leak detection system.

Fuel Tank Pressure Sensor Circuit High Input

The ECM has detected an unusually high voltage signal from the Fuel Tank Pressure (FTP) sensor, preventing the EVAP system from accurately monitoring for fuel vapor leaks.

O2 Sensor Heater Circuit Malfunction Bank 2 Sensor 1

Heater element fault in upstream O2 sensor Bank 2.

O2 Sensor Circuit Slow Response Bank 2 Sensor 2

Downstream O2 sensor bank 2 is responding too slowly.

O2 Sensor Circuit No Activity Bank 1 Sensor 2

Downstream O2 sensor shows no activity.

Secondary Air Injection System Insufficient Flow Bank 1

The ECM has detected insufficient airflow from the Bank 1 secondary air injection system, which pumps fresh air into the exhaust after cold start to help the catalytic converter reach operating temperature faster.

O2 Sensor Circuit Low Voltage Bank 1 Sensor 2

Downstream O2 sensor on Bank 1 reading consistently low voltage.

O2 Sensor Circuit High Voltage Bank 1 Sensor 2

Downstream O2 sensor on Bank 1 reading consistently high voltage.

O2 Sensor Circuit Slow Response Bank 1 Sensor 2

Downstream O2 sensor responds slowly — may indicate catalyst issue.

Evaporative Emission Control System Incorrect Purge Flow

The EVAP purge flow is not correct during the purge cycle.

Catalyst System Efficiency Below Threshold Bank 1

The catalytic converter on Bank 1 is not converting exhaust gases efficiently enough. The downstream O2 sensor is switching too rapidly, similar to the upstream sensor.

O2 Sensor Circuit High Voltage Bank 1 Sensor 1

Upstream O2 sensor on Bank 1 is reading rich (high voltage) all the time.

O2 Sensor Circuit No Activity Bank 1 Sensor 1

Upstream O2 sensor shows no voltage activity — stuck or dead.

Exhaust Gas Recirculation Sensor B Circuit Low

The secondary EGR position sensor (Sensor B) is reading a lower voltage than expected.

O2 Sensor Circuit Low Voltage Bank 1 Sensor 1

Upstream O2 sensor on Bank 1 is reading lean (low voltage) all the time.

Exhaust Gas Recirculation Flow Malfunction

General EGR flow fault. The EGR system recirculates exhaust gases to reduce NOx emissions.

Exhaust Gas Recirculation Circuit Malfunction

EGR control circuit fault.

O2 Sensor Circuit Slow Response Bank 1 Sensor 1

The upstream O2 sensor is not switching fast enough between rich and lean.

O2 Sensor Circuit Malfunction Bank 2 Sensor 1

Upstream O2 sensor circuit fault on Bank 2 (opposite side from cylinder 1).

Exhaust Gas Recirculation Insufficient Flow

Not enough EGR flow during operating conditions.

Exhaust Gas Recirculation Excessive Flow

Too much EGR flow detected.

Exhaust Gas Recirculation Circuit Range/Performance

EGR valve position does not match commanded position.

O2 Sensor Circuit Low Voltage Bank 2 Sensor 1

Upstream O2 sensor on Bank 2 reading lean (low voltage) constantly.

O2 Sensor Circuit Malfunction Bank 1 Sensor 1

The upstream oxygen sensor on Bank 1 has a circuit fault. This sensor controls the fuel mixture.

O2 Sensor Circuit High Voltage Bank 2 Sensor 1

Upstream O2 sensor on Bank 2 reading rich constantly.

O2 Sensor Circuit Slow Response Bank 2 Sensor 1

Upstream O2 sensor Bank 2 not switching fast enough.

O2 Sensor Circuit No Activity Bank 2 Sensor 1

No activity from upstream O2 sensor Bank 2.

Exhaust Gas Recirculation Sensor A Circuit Low

EGR position sensor A voltage is below expected range.

Exhaust Gas Recirculation Sensor A Circuit High

EGR position sensor A voltage is above expected range.

Exhaust Gas Recirculation Sensor B Circuit High

The secondary EGR position sensor (Sensor B) is reading a higher voltage than expected.

Catalyst System Efficiency Below Threshold Bank 2

Catalytic converter on Bank 2 is below efficiency threshold.

Exhaust Gas Recirculation Control Circuit High

The EGR valve control circuit is reading a higher voltage than expected.