NOx Sensor Circuit Low Input (Bank 1)
The P2202 code means the vehicle's onboard diagnostic system has detected: NOx Sensor Circuit Low Input (Bank 1). This is a moderate severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- hard
- Estimated cost
- $250 - $800 (parts and labor)
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Common Symptoms
- Check Engine Light on
- Emissions test failure
- Possible limp mode activation
- SCR system warning light
- Increased tailpipe emissions
Probable Causes (Ranked by Likelihood)
- Open circuit in NOx sensor wiring Very High
- Failed NOx sensor producing low signal High
- Corroded connector at the NOx sensor Moderate
- Ground fault in the sensor circuit Moderate
- ECM internal circuit fault Low
Step-by-Step Diagnostic Procedure
-
Check NOx sensor signal voltage with a scan tool -- should not read near zero at operating temperature
-
Inspect wiring from the NOx sensor to the ECM for open or short circuits
-
Clean or replace the sensor connector if corrosion is present
-
Test the sensor ground circuit for proper continuity
-
If wiring is good, replace the NOx sensor and recalibrate
Frequently Asked Questions
What does low input mean for a NOx sensor?
Low input means the voltage signal from the NOx sensor to the ECM is below the expected minimum threshold, indicating an open circuit, bad ground, or failed sensor.
Can a wiring repair fix P2202?
Yes, if the issue is a broken wire or corroded connector, repairing the wiring is often less expensive than replacing the entire NOx sensor.
Do I need a dealer scan tool to replace a NOx sensor?
In many cases, yes. NOx sensors on many vehicles require calibration or relearning with a factory or advanced aftermarket scan tool after replacement.
Sources
This page is built from documented references. Verify against your own service info before repair work.
P2202 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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