NOx Sensor Heater Control Circuit/Open Bank 1
The Powertrain Control Module (PCM) has detected an open circuit or electrical malfunction in the heater control circuit for the Nitrogen Oxide (NOx) sensor on Bank 1. This heater is essential for bringing the sensor to its optimal operating temperature quickly to accurately monitor exhaust emissions.
This code will not immediately strand you, but it will cause the vehicle to fail an emissions test. It should be diagnosed and repaired soon to ensure proper engine management and prevent potential long-term damage to the exhaust aftertreatment system.
Common symptoms
- Illuminated Check Engine Light
- Failed state emissions test
- Slight decrease in fuel economy
- Excessive soot or smoke from the exhaust (especially in diesels)
- Possible sluggish engine performance
Likely causes
- Internal failure of the Bank 1 NOx sensor heater element
- Damaged, frayed, or broken wiring in the NOx sensor heater circuit
- Corroded, loose, or damaged electrical connector at the NOx sensor
- Blown fuse or faulty relay providing power to the NOx sensor heater
- Faulty Powertrain Control Module (PCM) or software issue (rare)
What to check before replacing parts
Visually inspect the NOx sensor wiring harness and connector on Bank 1.
Look for: Look for melted wires, chafing, corrosion in the pins, or a loose connection that could cause an open circuit.
Check the fuses and relays associated with the emissions or NOx sensor heater circuits.
Look for: A blown fuse indicates a short circuit that needs to be addressed before replacing the fuse or sensor.
Measure the resistance of the NOx sensor heater element using a multimeter.
Look for: An infinite resistance (OL) reading indicates the internal heater element is broken (open) and the sensor must be replaced.
Verify power supply to the NOx sensor heater circuit with the key on.
Look for: You should see battery voltage (approximately 12V) at the power supply pin; lack of voltage indicates a wiring or supply issue upstream.
Test the ground circuit for the NOx sensor heater.
Look for: A high resistance or lack of continuity to ground indicates a wiring fault between the sensor connector and the chassis ground or PCM.
This page explains the generic P2205 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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