P1138 Fault Code

Audi – Long-Term Fuel Trim

For both Audi and Volkswagen, fault code P1138 indicates that the fuel trim is too lean for bank 2 of the engine.

Long-term fuel trim is a term used by some manufacturers that refers to the oxygen sensors that are found downstream of the catalytic converter.

The exhaust fumes are monitored even here to relay information to the powertrain control module and ensure there are no issues in the exhaust system.

Bank 2 refers to the side of the engine opposite the first cylinder. This code does not apply to straight or inline engines.

See similar generic code: P2096, P2098

BMW – Oxygen Sensor Heater Circuit Low Voltage (Bank 1 Sensor 2)

For BMW, fault code P1138 indicates that the heater circuit for the downstream heated oxygen sensor is malfunctioning. This code means that the voltage signal sent from the sensor to the powertrain control module is too low.

Heated oxygen sensors contain a heater circuit that brings them up to operating temperatures shortly after the engine is turned on. This helps provide more accurate readings to the PCM.

A low voltage from the heater circuit can mean the sensor in question cannot properly heat up, causing issues with the reading it sends to the PCM.

Bank 1 refers to the side of the engine in which the first cylinder is located. Sensor 2 indicates that this is the heated oxygen sensor that is downstream from the catalytic converter.

See similar generic code: P0037

Ford – Lack of Downstream Heated Oxygen Sensor Switch – Sensor Indicates Rich – Bank No. 1

For Ford, fault code P1138 is logged when the heated oxygen sensor detects that the exhaust fumes are too rich.

Running rich is a term used to describe when the air-fuel mixture in the engine has too much fuel and not enough air. The ideal fuel ratio for an internal combustion engine is 14.7 parts of air to every 1 part of fuel.

The heated oxygen sensors monitor the exhaust fumes and relay information to the powertrain control module. This information is then used to optimize how the engine runs.

The downstream heated oxygen sensor, also called sensor 2, is found after the catalytic converter.

See similar generic code: P2097, P2099

Land Rover – Oxygen Sensor Engine Rich *Codes* A D

For Land Rover, fault code P1138 indicates that the oxygen sensor after the catalytic converter is showing that the engine is running rich.

Running rich is a term used to describe when the air-fuel mixture in the engine has too much fuel and not enough air. The ideal fuel ratio for an internal combustion engine is 14.7 parts of air to every 1 part of fuel.

The heated oxygen sensors monitor the exhaust fumes and relay information to the powertrain control module. This information is then used to optimize how the engine runs.

The downstream heated oxygen sensor, also called sensor 2, is found after the catalytic converter.

See similar generic code: P2097, P2099

Chrysler – Heated Oxygen Sensor Bank 1 Sensor 2 Signal Above 0.45 V (A/F Ratio Too Rich)

For Chrysler, fault code P1133 is logged when the powertrain control module has detected that the heated oxygen sensor after the catalytic converter indicates a running-rich condition.

The voltage reading indicates that the exhuast fumes are too rich.

Running rich is the term used to indicate when the air-fuel mixture has too much fuel and not enough air in it. The ideal fuel ratio for an internal combustion engine is 14.7 parts of air to every 1 part of fuel.

See similar generic code: P2097, P2099

Volkswagen – Long-Term Fuel Trim Add. Fuel B2 System Too Lean

This code is used by both Audi and Volkswagen to represent the same issue in their vehicles. For more information, see the Audi description

See similar generic code: P2096, P2098