Nox Sensor Current Fault
The NOx sensor has detected an out-of-range signal indicating a fault.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The NOx sensor measures nitrogen oxides in the exhaust; if it sees a reading that doesn’t make sense, like showing too high or too low for the conditions, it triggers this code.
What the computer is actually seeing
The engine control module (ECM) compares the voltage readings from the NOx sensor against reference values. It expects a specific voltage range under normal operating conditions. If it sees outside of this, it flags a fault.
What a healthy reading looks like
Normal voltage is typically between 0.2V to 2.0V under various operating conditions; outside this range is considered a fault.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Inspect the wiring and connectors to the NOx sensor for any damage or corrosion. If found, repair or replace as necessary. Check wiring for short to ground or open circuits.
- 22. Use a multimeter to measure the sensor voltage while the engine is running. Ensure it falls between 0.2V and 2.0V under various RPMs.
- 33. Check for exhaust leaks between the engine and the NOx sensor. If leaks are found, repair them and retest.
- 44. Replace the NOx sensor if the voltage readings are out of range and wiring is confirmed to be good. Confirm with a scan tool that the code clears.
Common causes
- Faulty NOx sensor
- Wiring issues or corrosion in connectors
- Exhaust leaks near the NOx sensor
- ECM calibration issue
Typical repair cost
$$ - $$$
Related codes
Frequently asked questions
Can I drive my vehicle with this code?
Yes, but fix it soon as it can impact emissions and performance.
Will this code come back after clearing it?
If the underlying issue isn't addressed, yes, it will likely return.
Why is this code paired with other SPN codes?
These codes may indicate related problems in the exhaust or emissions system.
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