Powertrain, generic · Auxiliary emission controls

P041C EGR Temperature Sensor B Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

EGR temperature sensor B measures the gas temperature in the EGR path – for cooler monitoring, component protection and the EGR model. Whether it sits before or after the cooler depends on the maker: GM diesels have sensor A after and B before the cooler, Ford diesels sensor B after it. Like a coolant sensor it is an NTC, so a low voltage means hot. P041C means the signal is below its lower limit – very hot or shorted to ground; Ford puts below 0.10 V at about 961 °C. Thresholds: Ford diesel below 0.10 V for 3 s, Ford petrol below 0.32 V for 5 s, GM's Duramax LML below 0.46 V for 5 s, GM 2018 a resistance below 164 Ω; MIL after two trips. A substitute value is used and the EGR cooler check (P2457) is suspended.

Likely causes

Signal wire shorted to ground
Sensor shorted internally
Moisture in the connector
Actual overtemperature (cooler or coolant problem)

Symptoms

  • Check engine light on
  • Usually no change in driving
  • Substitute value used, EGR cooler check suspended

Repair estimate

DifficultyEasyDIY possible
Parts and labour€50–250
Time0.5–1.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

egr temperature sensor begr coolersensor wiringengine control module

Related codes

P041AP041BP041DP041EP040C

References: fordservicecontent.com, fordservicecontent.com, gsi.ext.gm.com, gsi.ext.gm.com.