EGR B Flow
The exhaust-gas recirculation system has a second EGR loop (B) - typically used on engines with a dedicated low-pressure EGR for emissions or on twin-bank V engines. The ECU detects an EGR B flow fault - the measured or modelled flow does not match the requested rate, without yet diagnosing it as too low or too high.
Affected components
- Egr valve b
- Egr cooler b
- Egr position sensor b
Common causes
- High likelihood: EGR valve B sticking due to soot
- Medium likelihood: EGR cooler B partially clogged
- Low likelihood: Flow or position sensor drift
Possible symptoms
- Check engine light on
- Pinging or knocking under load
- Power loss and hesitation
- Possible rough idle
- Failed emissions inspection (NOx)
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.