What it means
EGR temperature sensor B above upper plausibility — open signal or short to B+. 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 position in the EGR path. The control module monitors the signal and sets P041D when it rises above the expected upper limit, often because the signal wire is open or shorted to a power source; this is the high-signal fault for sensor B.
Common causes
Most likely first.
- Open signal line
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
Symptoms
- Check engine light on
- Possible EGR-related drivability issues
How to diagnose it
- Review freeze-frame data and live sensor B readings to confirm the signal is abnormally high and identify when the fault was recorded.
- Inspect sensor B's connector and wiring for a loose connection, corrosion, a broken signal wire, or insulation damaged against a power source.
- Check whether the high reading changes as the harness is gently moved, which may expose a loose terminal or intermittent open.
- Test the signal circuit for an open and for an unintended short to power, following the vehicle wiring information.
- Test sensor B and its circuit against the manufacturer's specification to separate a failed sensor from a wiring fault.
Common fixes
- Reconnect and secure a loose sensor B connector.
- Repair an open signal wire or wiring short to power.
- Clean or repair corroded or damaged connector terminals.
- Replace sensor B if it fails its test and the circuit is sound.
Can I keep driving?
If there is no rough running or other warning, gentle short-distance driving is generally possible while you arrange a repair. Avoid heavy loads if EGR-related symptoms appear, since faulty EGR control can affect drivability and emissions.
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.