NOx Sensor Circuit Range/Performance (Bank 1)
The P2201 code means the vehicle's onboard diagnostic system has detected: NOx Sensor Circuit Range/Performance (Bank 1). This is a moderate severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- hard
- Estimated cost
- $300 - $900 (parts and labor)
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Common Symptoms
- Check Engine Light on
- Failed emissions inspection
- Reduced engine power
- SCR system malfunction warning
- Increased exhaust emissions
Probable Causes (Ranked by Likelihood)
- Degraded or failing NOx sensor on Bank 1 Very High
- Exhaust leak near the NOx sensor location High
- Contaminated sensor from engine oil consumption Moderate
- Poor quality or depleted DEF fluid (diesel) Moderate
- SCR catalyst efficiency loss Low
Step-by-Step Diagnostic Procedure
-
Compare NOx sensor readings to expected values at various engine loads
-
Check for exhaust leaks near the sensor mounting location
-
Inspect for signs of oil or coolant contamination in the exhaust
-
If diesel, test DEF quality with a refractometer
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Monitor SCR conversion efficiency with a scan tool
Frequently Asked Questions
What is the difference between P2200 and P2201?
P2200 indicates a general circuit fault with the NOx sensor, while P2201 specifically indicates the sensor output is out of the expected range or not performing correctly, even though the circuit itself may be intact.
Can bad DEF fluid cause P2201?
Yes, on diesel vehicles with SCR systems, degraded or contaminated DEF fluid can cause incorrect NOx readings and trigger this code.
How long does a NOx sensor last?
NOx sensors typically last 100,000 to 150,000 miles, but exposure to contaminants like oil, coolant, or poor DEF quality can shorten their lifespan significantly.
Sources
This page is built from documented references. Verify against your own service info before repair work.
P2201 on Diesel, EV & Equipment
The same code ID appears across other engines and platforms. The diagnostic flow varies by manufacturer — these are the platform-specific breakdowns:
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