SCR NOX Sensor Circuit
There’s a fault in the SCR NOx sensor circuit.
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 oxide levels to help control emissions. If it detects incorrectly, the system can think there's an issue with emissions control, triggering a warning.
What the computer is actually seeing
The Engine Control Module (ECM) monitors the NOx sensor's voltage signal, which should be between 0.5V and 4.5V in normal operation. If the signal is out of this range, or if the sensor is unresponsive, a fault code is generated.
What a healthy reading looks like
Normal NOx sensor voltage range is typically between 0.5V and 4.5V corresponding to NOx levels. If the sensor is functioning properly, expected response time for the 5V signal to stabilize should be less than 200 ms.
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.
- 1Check the wiring and connectors for the NOx sensor for any visible damage or corrosion. If damaged, repair or replace as necessary. Decision point: If wiring is intact, proceed to next step.
- 2Using a multimeter, check the voltage at the NOx sensor connector. You should see a voltage between 0.5V and 4.5V with the engine running. Decision point: If the voltage is outside this range, the sensor may be faulty. If the voltage is within range, proceed to next step.
- 3Inspect for any exhaust leaks near the NOx sensor that could affect readings. Seal any leaks found. Decision point: If leaks are present and fixed, monitor for code return. If no leaks, proceed to next step.
- 4If no issues found in previous steps, consider the possibility of a faulty NOx sensor itself. Replace the sensor and clear codes. Decision point: Did the code return after replacement? If yes, suspect ECM or wiring fault.
Common causes
- Wiring issues (shorts or opens) in the NOx sensor circuit
- Faulty NOx sensor
- Connector corrosion or poor contact
- Exhaust leaks affecting sensor accuracy
- ECM software issues
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Yes, but emissions may be higher than normal and it's advisable to fix soon.
Will this code come back after clearing?
If the underlying issue isn't resolved, yes, it will likely return.
Why is this paired with other NOx codes?
These codes relate to similar sensor or circuit faults, often appearing together.
Working a real vehicle right now?
Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.
Start guided diagnostic →