U04A4 – BMW DTC

BMW DTC U04A4 – Invalid Data Received From PM Sensor

DTC U04A4 meaning on BMW

The DTC U04A4 code on a BMW indicates that the vehicle’s onboard diagnostic system has detected invalid data being received from the PM (Particulate Matter) sensor. The PM sensor is responsible for monitoring the level of particulate matter in the exhaust system, which is crucial for emissions control and overall engine performance.

BMW DTC U04A4 symptoms

Symptoms associated with the DTC U04A4 code on a BMW may include:

• Check Engine Light (MIL) illuminated on the dashboard
• Decreased fuel efficiency
• Engine running rough or misfiring
• Reduced engine power

BMW DTC U04A4 causes

The DTC U04A4 code on a BMW can be triggered by various factors, including:

• Malfunctioning PM sensor
• Wiring or connection issues in the sensor circuit
• Software glitches in the engine control module
• Excessive particulate matter buildup in the exhaust system

BMW DTC U04A4 seriousness

The DTC U04A4 code should not be ignored, as it can lead to increased emissions, reduced engine performance, and potential damage to the catalytic converter. Addressing this issue promptly is essential to maintain the vehicle’s efficiency and compliance with emissions regulations.

How to diagnose DTC U04A4 on BMW

To diagnose the DTC U04A4 code on a BMW, a mechanic may perform the following steps:

1. Use a diagnostic scanner to retrieve the fault codes stored in the vehicle’s computer
2. Inspect the PM sensor and its wiring for any visible damage or corrosion
3. Check the sensor’s readings using specialized diagnostic equipment
4. Verify the integrity of the sensor’s signal and power supply

How to fix DTC U04A4 on BMW

Fixing the DTC U04A4 code on a BMW may involve the following actions:

1. Replace the faulty PM sensor if it is determined to be malfunctioning
2. Repair any damaged wiring or connections in the sensor circuit
3. Update the engine control module software to address any programming issues
4. Clean or replace the particulate filter in the exhaust system if necessary

How to erase DTC U04A4 on BMW

To erase the DTC U04A4 code on a BMW, follow these steps:

1. Use a diagnostic scanner to clear the fault codes stored in the vehicle’s computer
2. Ensure that the underlying issue causing the code has been resolved
3. Perform a test drive to confirm that the code does not reappear

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.