BMW DTC P1204 – O2 Sensor Circuit Full Load Test Signal Too Low (Bank 1 Sensor 2)
DTC P1204 meaning on BMW
DTC P1204 on a BMW indicates that the O2 sensor circuit full load test signal for Bank 1 Sensor 2 is too low. This means that the signal from the downstream oxygen sensor in Bank 1 is not within the expected range during full load conditions.
BMW DTC P1204 symptoms
Symptoms of DTC P1204 on a BMW may include:
- Check Engine Light (MIL) illuminated
- Decreased fuel efficiency
- Engine running rough or misfiring
- Reduced engine performance
BMW DTC P1204 causes
Common causes of DTC P1204 on a BMW include:
- Faulty oxygen sensor (Bank 1 Sensor 2)
- Wiring or connector issues in the O2 sensor circuit
- Exhaust leaks near the downstream oxygen sensor
- Engine running too rich or too lean
BMW DTC P1204 seriousness
While DTC P1204 may not cause immediate drivability issues, it can lead to decreased fuel efficiency and potentially cause damage to the catalytic converter over time if left unresolved. It is recommended to address this issue promptly.
How to diagnose DTC P1204 on BMW
To diagnose DTC P1204 on a BMW, you can:
- Use a scan tool to retrieve the fault code and freeze frame data
- Inspect the wiring and connectors in the O2 sensor circuit for damage or corrosion
- Check for exhaust leaks near the downstream oxygen sensor
- Test the Bank 1 Sensor 2 oxygen sensor using a multimeter
How to fix DTC P1204 on BMW
To fix DTC P1204 on a BMW, you may need to:
- Replace the Bank 1 Sensor 2 oxygen sensor if it is faulty
- Repair any damaged wiring or connectors in the O2 sensor circuit
- Address any exhaust leaks near the downstream oxygen sensor
- Perform a full load test to ensure the signal is within the correct range
How to erase DTC P1204 on BMW
To erase DTC P1204 on a BMW, you can:
- Use a scan tool to clear the fault code after the issue has been resolved
- Ensure that the repair has been successful by performing a test drive and monitoring for any reoccurrence of the fault code
Recommended tools & DTC Scanners for BMW
Best Diagnostic App for modern BMWs: BimmerLink
Recommended Bluetooth adapter for Bimmerlink: OBDLink CX
Cable adapter for Bimmerlink: Enet Cable USB Type C
For older BMWs we recommend: Autel AutoLink AL319 (2024 version)
Easy-to-use Multimeter for reliable diagnostics: AstroAI Auto-ranging Multimeter
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