O2 Sensor Signals Swapped Bank 1 Sensor 1 / Bank 2 Sensor 1
2018-2018 Audi A6 3.0L Supercharged V6
The 2018 Audi A6 is equipped with a 3.0L V6 engine. Below you'll find detailed p0040 diagnostic code information including labor time estimates, cost ranges, and technician notes specific to this engine configuration.
Description
The PCM has determined that the upstream O2 sensor signals for Bank 1 and Bank 2 are swapped, likely due to incorrect wiring after sensor replacement.
Symptoms
- Check Engine Light
- Poor fuel economy
- Rough running
- Failed emissions
Common Causes
- O2 sensor connectors swapped after service
- Wiring crossed between banks
- Incorrect sensor installation
Diagnostic Steps
- Verify which O2 sensor is connected to which bank
- Trace wiring from each sensor to PCM connector
- Check for crossed connectors
Repair Notes
Swap the sensor connectors to the correct banks.
Related Codes
Other Powertrain Codes
- P0001Fuel Volume Regulator Control Circuit/Open
- P0002Fuel Volume Regulator Control Circuit Range/Performance
- P0003Fuel Volume Regulator Control Circuit Low
- P0004Fuel Volume Regulator Control Circuit High
- P0010Intake Camshaft Position Actuator Circuit/Open Bank 1
- P0011Intake Camshaft Position Timing Over-Advanced Bank 1
- P0012Intake Camshaft Position Timing Over-Retarded Bank 1
- P0013Exhaust Camshaft Position Actuator Circuit/Open Bank 1
- P0014Exhaust Camshaft Position Timing Over-Advanced Bank 1
- P0015Exhaust Camshaft Position Timing Over-Retarded Bank 1
P0040 on Other Vehicles
Common Questions
What does code P0040 mean on a 2018-2018 Audi A6?
P0040 stands for "O2 Sensor Signals Swapped Bank 1 Sensor 1 / Bank 2 Sensor 1". The PCM has determined that the upstream O2 sensor signals for Bank 1 and Bank 2 are swapped, likely due to incorrect wiring after sensor replacement.
What are the symptoms of P0040 on a Audi A6?
Common symptoms of P0040 include: Check Engine Light, Poor fuel economy, Rough running, Failed emissions.
What causes P0040 on a 2018-2018 Audi A6?
Common causes of P0040 include: O2 sensor connectors swapped after service, Wiring crossed between banks, Incorrect sensor installation.
Last updated: March 2026