Powertrain, generic · Auxiliary emission controls

P046E EGR Sensor B Circuit Range/Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

Exhaust gas recirculation (EGR) routes part of the exhaust back into the intake to lower combustion temperature and NOx. Which part EGR sensors A and B are depends on the maker: sensor A is usually the position sensor of EGR valve A; GM's Duramax diesels of 2017/18 use sensor B for the coolant temperature sensor at the inlet of the high-pressure EGR cooler, FCA for the position sensor of the low-pressure valve. P046E means the signal of sensor B is valid but implausible. On GM's Duramax diesels, where it is the cooler inlet coolant temperature, the module compares it at a cold start after at least 8 hours off with two charge air temperature sensors; a deviation above 10 °C sets the code once per trip, MIL after two trips. A substitute value is then used and the EGR cooler check (P2457) is suspended.

Likely causes

Temperature sensor drifting
Contact resistance at the connector
Reference sensor (charge air temperature) inaccurate without its own code
Low coolant or air at the sensor

Symptoms

  • Check engine light on
  • Usually no change in driving
  • EGR cooler check suspended

Repair estimate

DifficultyEasyDIY possible
Parts and labour€40–300
Time0.5–1.5 h

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

Parts involved

egr sensor begr cooler coolant temperature sensorsensor wiringengine control module

Related codes

P046FP0407P0408P046CP2457

References: gsi.ext.gm.com, gsi.ext.gm.com, law.cornell.edu, static.nhtsa.gov.