U05A1

Q: Can I keep driving with this code?

The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical. Use the Wrenchify app for a full diagnosis specific to your vehicle.

NOx Sensor A Received Invalid Data From ECM/PCM

High severity

NOx sensor A (smart sensor with own ECU) received implausible data from the ECM/PCM. Engine load, fuel rate or temperature data needed for the sensor's internal compensation fails plausibility checks; the sensor reports degraded readings.

Common causes

ECM/PCM internal fault or sensor input drift
One of the most commonly reported causes for this code — check this first.
high
Typical part cost: $220-2750
Software version mismatch after replacement
A plausible cause — test and verify before replacing parts.
medium
Typical part cost: $220-2750
See all causes + fix costs
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First things to check

1Confirm the code with a scan tool and check for additional related codes.
2Inspect the relevant sensors, wiring, and connectors for damage or corrosion.

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Related codes

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Frequently asked questions

What does U05A1 mean?

U05A1 means "NOx Sensor A Received Invalid Data From ECM/PCM". It is a generic OBD-II code that points to a fault in the network / communication.

What are the most common causes of U05A1?

ecm/pcm internal fault or sensor input drift; software version mismatch after replacement; gateway module routing can messages incorrectly — these are the most commonly reported causes. Verify with a proper diagnosis before replacing parts, or use the Wrenchify app for a vehicle-specific diagnosis.

Can I keep driving with this code?

This code can put the vehicle into limp or reduced-power mode. Avoid extended driving and have the vehicle diagnosed promptly. Use the Wrenchify app for a full diagnosis specific to your vehicle.

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