P0040
O2 Sensor Signals Swapped Bank 1 Sensor 1/Bank 2 Sensor 1
Generic code
Fuel and Air Metering
Medium severity
Moderate repair
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What P0040 means
- The fault code P0040 indicates that the signals of oxygen sensors of bank 1 sensor 1 and bank 2 sensor 1 are swapped. This can lead to incorrect fuel trims, decreased fuel efficiency, and increased emissions.
Possible symptoms
- Decreased fuel efficiency
- Illuminated check engine light
- Rough idle or stalling
- Poor engine performance
- Increased emissions.
Possible causes
- Swapped oxygen sensor wiring or connectors
- Failed oxygen sensor
- Failed engine control module (ECM)
- Malfunctioning oxygen sensor heater circuit
Related parts
- Oxygen Sensor: This is one of the parts that fails very commonly. It measures the amount of oxygen to ensure proper combustion. Problems in the Oxygen Sensor lead to poor fuel economy
Possible solutions
- Check and correct wiring and connections for oxygen sensors
- Replace the oxygen sensor(s)
- Replace the engine control module (ECM) if necessary
- Check and repair any issues with the oxygen sensor heater circuit.
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P0040 on OBD DashX
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