BMW DTC P1143 – O2 Sensor Activity Check Signal Too High (Bank 1 Sensor 2)
DTC P1143 meaning on BMW
The DTC P1143 on a BMW indicates that the O2 Sensor Activity Check Signal for Bank 1 Sensor 2 is reading too high. This means that the signal from the downstream oxygen sensor located after the catalytic converter in bank 1 is registering a voltage that is outside of the expected range.
BMW DTC P1143 symptoms
Symptoms of a DTC P1143 on a BMW may include poor fuel economy, rough idling, hesitation during acceleration, and an illuminated Check Engine Light on the dashboard.
BMW DTC P1143 causes
The most common causes of a DTC P1143 on a BMW are a faulty oxygen sensor, a vacuum leak in the exhaust system, a damaged catalytic converter, or issues with the engine’s air-fuel mixture.
BMW DTC P1143 seriousness
While a DTC P1143 may not cause immediate drivability issues, it can lead to decreased fuel efficiency and increased emissions. Ignoring this fault code can potentially cause damage to the catalytic converter over time.
How to diagnose DTC P1143 on BMW
To diagnose a DTC P1143 on a BMW, a mechanic would typically use a diagnostic scanner to retrieve the fault code and then perform a visual inspection of the oxygen sensor and the exhaust system for any visible damage or leaks. Additionally, testing the sensor’s voltage output and checking for any underlying issues with the engine’s performance may be necessary.
How to fix DTC P1143 on BMW
Fixing a DTC P1143 on a BMW usually involves replacing the faulty oxygen sensor, repairing any vacuum leaks in the exhaust system, addressing issues with the catalytic converter if necessary, and ensuring that the engine’s air-fuel mixture is within the correct parameters.
How to erase DTC P1143 on BMW
Once the underlying issue causing the DTC P1143 on a BMW has been resolved, the fault code can be cleared using a diagnostic scanner. This will reset the Check Engine Light and allow the vehicle’s onboard computer to monitor the system for any new faults.
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
Some of the links on this page may be affiliate links, which means we may earn a small commission if you make a purchase. This helps us keep our DTC database up to date and provide valuable content for free. We only recommend products that we have tested and believe to be the best in their class.