Common Symptoms
- Check engine light illuminated
- Poor fuel economy
- Increased diesel exhaust emissions
- DEF system warning messages on instrument cluster
- Vehicle may enter derate or limp mode
- Failed emissions test
Most Likely Root Causes
- Failed NOx sensor heater element
- Damaged wiring harness to NOx sensor
- Corroded or loose NOx sensor electrical connector
- Faulty NOx sensor module
- ECM software issue or internal ECM fault
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Component Location
NOx sensor is typically located in the exhaust system downstream of the DPF or SCR catalyst on diesel vehicles with selective catalytic reduction systems.
Manufacturer Notes
NOx sensors on diesel aftertreatment systems require proper warm-up cycles and may set heater codes during cold ambient conditions or short drive cycles.
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