Universal (All Makes) Vehicle (OBD-II)
Severity:Common Causes
- map[cause:Open circuit in the NOx sensor signal wire]
- map[cause:Short to power (voltage) in the sensor wiring harness]
- map[cause:Defective NOx sensor stuck at high output]
- map[cause:Poor ground connection at the sensor or ECM]
- map[cause:Water or moisture intrusion into the sensor connector]
How to Fix It
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Scan for codes and note if any other NOx or O2 sensor codes are present.
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Inspect the sensor wiring for any obvious damage, chafing, or open wires.
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Check all ground points related to the sensor circuit.
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Test signal wire continuity from sensor to ECM with a multimeter.
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Replace the NOx sensor if wiring checks out fine and fault persists.
Frequently Asked Questions
What does 'circuit high' mean?
It means the sensor is sending a voltage above the maximum expected value. This usually points to an open wire or a short to power.
Can moisture cause P2203?
Yes. Water in the connector can temporarily bridge circuits. Dry out the connector and apply dielectric grease as a preventive measure.
Is P2203 a serious problem?
It's a medium-severity emissions code. The car will usually run, but it may fail an emissions test. Repair it before your next inspection.