P0040moderate severityPowertrain
O2 Sensor Signals Swapped Bank 1 Sensor 1 / Bank 2 Sensor 1
on 2002 Saab 9-3 2.0L I4 Turbo · FWD
What this code means
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.
Other Powertrain codes on this vehicle
P0001
Fuel Volume Regulator Control Circuit/Open
P0002
Fuel Volume Regulator Control Circuit Range/Performance
P0003
Fuel Volume Regulator Control Circuit Low
P0004
Fuel Volume Regulator Control Circuit High
P0010
Intake Camshaft Position Actuator Circuit/Open Bank 1
P0011
Intake Camshaft Position Timing Over-Advanced Bank 1
P0012
Intake Camshaft Position Timing Over-Retarded Bank 1
P0013
Exhaust Camshaft Position Actuator Circuit/Open Bank 1
P0014
Exhaust Camshaft Position Timing Over-Advanced Bank 1
P0015
Exhaust Camshaft Position Timing Over-Retarded Bank 1