U04A4: Invalid Data Received From Particulate Matter Sensor A

What it means

A control module received invalid data from particulate matter sensor A. The code identifies a data validity fault; the specific affected function depends on the vehicle.

At a glance

• Usually lights the warning light of the system that lost communication
• Affects emissions; the car can fail an emissions test

How it works

Particulate matter sensor A monitors soot-related material in the exhaust and sends its readings through a control module to other vehicle systems. This code sets when a receiving module judges the data from sensor A invalid; it does not specifically indicate a blocked filter or a high or low sensor reading.

Common causes

Most likely first.

1. Fault in the transmitting module or sensor
2. Network wiring or connector fault
3. Module power or ground fault
4. Software or configuration issue

Symptoms

• An emissions or engine warning may appear
• Emissions control may be affected

How to diagnose it

1. Record freeze-frame data and scan all modules for particulate matter sensor, exhaust after-treatment, and network codes to identify the reporting module and conditions.
2. Review live data for particulate matter sensor A and compare its readings with related exhaust or filter data as the engine warms and operates.
3. Inspect sensor A's exhaust-side installation, connector, and harness for soot leakage, heat damage, corrosion, or chafing.
4. Check the sensor's module power and ground and the relevant network wiring and connectors for poor connections, opens, or shorts.
5. If wiring and supplies are sound, use the manufacturer's procedure to assess sensor A and the transmitting module, including applicable software or configuration checks.

Common fixes

• Repair damaged, loose, or corroded wiring or connectors for particulate matter sensor A.
• Repair an exhaust leak or damaged sensor mounting that affects sensor A's readings, if found.
• Restore a faulty power or ground connection to the sensor's transmitting module.
• Replace particulate matter sensor A if testing confirms it is producing invalid data.
• Correct a software or configuration mismatch or repair the transmitting module if diagnosis identifies it.

Can I keep driving?

If the vehicle runs normally, a short drive may be possible, but emissions monitoring or control may be affected. Avoid hard or extended driving if engine or emissions warnings appear, and address the fault before relying on the vehicle to meet an emissions test.