NOx Sensor Heater Sense Circuit Range/Performance (Bank 2)

Possible causes

• CommonFailed heater element inside the NOx sensor
• CommonCorroded connector at the sensor
• CommonWiring damaged by exhaust heat
• PossibleBlown fuse on the heater circuit
• PossibleWater reaching a hot sensor and cracking the element
• RareFailed control module driver

What you might notice

• Check engine light on
• Reduced power or limp mode
• Emissions system warning
• Restart countdown on some vehicles
• Failed emissions test
• Often no symptom the driver notices at first

What to check, in order

1. Check the fuse for the heater circuit before anything else.
2. Inspect the connector for corrosion and heat damage.
3. Measure the heater element resistance against specification.
4. Check the wiring where it runs along the exhaust.
5. Note that the heater is usually integral to the sensor. If the element has failed, the sensor is the repair - so eliminate the wiring and fuse first, because the sensor is expensive.