NOx Sensor Circuit High Bank 1
The P2203 code indicates that the Engine Control Module (ECM) has detected a voltage signal from the NOx sensor on Bank 1 that is higher than the expected range. This sensor monitors nitrogen oxide levels in the exhaust to optimize diesel exhaust fluid (DEF) injection and reduce emissions. A high circuit condition typically points to a wiring issue, a faulty sensor, or a problem with the sensor's power or ground circuit.
01. Most Common Causes
- Faulty NOx sensor
- Short to voltage in sensor wiring
- Open or high resistance in sensor ground circuit
- Corroded or damaged connector
- ECM software or hardware issue
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced fuel economy
- Increased emissions
- Possible limp mode activation
- Failed emissions test
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to retrieve freeze frame data and confirm the code.
Step 2: Visually inspect the NOx sensor connector and wiring for damage, corrosion, or shorts.
Step 3: Measure voltage at the sensor connector with the ignition on; compare to manufacturer specifications.
Step 4: Check the sensor ground circuit for continuity and low resistance.
Step 5: If wiring is okay, replace the NOx sensor and clear the code; retest to see if code returns.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is generally not recommended to drive long distances with this code, as it can lead to reduced engine performance, increased emissions, and potential damage to the aftertreatment system. However, short trips to a repair shop are usually acceptable.
How much does it cost to fix?▼
The cost to fix a P2203 code typically ranges from $200 to $600, including parts and labor. The NOx sensor itself costs $100-$300, and labor adds $100-$300 depending on the vehicle and shop rates.