P241F
EGR Cooler B Efficiency Below Threshold
The temperature drop across EGR cooler B is below the calibrated threshold - cooler is fouled with soot, has internal scaling, or coolant flow is restricted. Recirculated gas reaches the intake hotter than designed, increasing NOx and combustion temperatures.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Symptoms
- Check engine light on
- Pinging or knocking under load
- Power loss and hesitation
- Possible rough idle
- Failed emissions inspection (NOx)
Common causes
Ordered by how often each turns out to be the cause.
- Cooler fouled with soot or scaledCommon
Parts involved
- EGR Cooler B
P241F is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.