Powertrain, generic · Auxiliary emission controls

P041B EGR Temperature Sensor B Circuit Range/Performance

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. P041B is its plausibility check. Ford diesels compare it at a cold start, after at least 6 hours off, with two other air temperatures (limit 25 °C, 30 °C with a block heater); GM diesels set the code if it barely changes after 8 hours off and EGR operation. Ford petrol engines list P041B with the electrical checks (5 s). MIL after two trips.

Likely causes

Sensor drifting or sluggish (soot)
Contact resistance in the connector
No EGR flow (GM stuck test)
Comparison sensor (intake or charge air temperature) faulty

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

P041AP041CP041DP040BP040F

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