P041E: EGR Temperature Sensor B Circuit Intermittent/Erratic

What does P041E mean?

Exhaust gas recirculation (EGR) routes part of the exhaust back into the intake to lower combustion temperature and NOx. EGR temperature sensor B is the second temperature sensor in the EGR path; on GM diesels it sits before the cooler, on Ford diesels after it. P041E means its signal jumps. GM's diesels of 2016–18, the only documented users, set it when the measured resistance changes by more than 25 Ω between two samples 100 ms apart – faster than any real temperature change, so a loose contact or cracked sensor is the cause (40 of 50 samples, MIL after two trips). Dependent checks such as EGR cooler efficiency are then suspended.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Check engine light on, may come and go
• Usually no noticeable symptom
• Further EGR temperature or cooler checks suspended

Common causes

• High Loose contact or corrosion at the sensor connector
• Medium Harness chafed or broken (heat at the EGR pipe)
• Medium Sensor cracked internally (thermal cycling)
• Low Engine module or ground connection

Likelihood is a general estimate across vehicles; your make and model may differ.