What it means
EGR temperature sensor B below lower plausibility — short to ground. EGR mixes inert exhaust into intake to lower combustion peak temperature — too little raises NOx, too much causes misfires and rough running.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
EGR temperature sensor B measures exhaust temperature at its location in the exhaust gas recirculation path. The control module monitors its signal voltage and sets P041C when the reading falls below the expected lower limit, commonly because the signal is shorted to ground; the code concerns sensor B, not sensor A.
Common causes
Most likely first.
- Short to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
Symptoms
- Check engine light on
- Possible EGR-related drivability issues
How to diagnose it
- Check freeze-frame data and live sensor B readings to confirm the low signal is present and note the operating conditions when it occurs.
- With the ignition off, inspect sensor B's connector and harness for moisture, corrosion, pin damage, or insulation rubbed through to ground.
- Check whether sensor B's reading changes when the harness is gently moved, which can reveal an intermittent short or damaged section.
- Test the signal wire for a short to ground and inspect connector continuity using the vehicle wiring information.
- Measure sensor B and its circuit against the manufacturer's specification to determine whether the sensor or wiring is pulling the signal low.
Common fixes
- Repair chafed wiring that is shorting sensor B's signal to ground.
- Clean or repair corroded connector pins and ensure they seat correctly.
- Repair a damaged connector or harness section.
- Replace sensor B if its electrical test fails while the wiring checks out.
Can I keep driving?
If the vehicle runs normally, you can usually drive it gently for a short time, but arrange diagnosis soon and avoid sustained heavy loads if rough running occurs. Incorrect EGR control can raise emissions and contribute to drivability problems.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.