What it means
The control module detects that EGR cooler B efficiency is below its calibrated threshold. The code does not by itself establish soot buildup, restricted coolant flow, or increased combustion temperature.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
EGR cooler B transfers heat from exhaust gas recirculation flow into engine coolant before the exhaust returns to the intake. The module compares temperature information to estimate cooler B efficiency and sets this code when the measured heat transfer falls below its calibrated threshold; the code alone does not prove why.
Common causes
Most likely first.
- Restricted or leaking EGR cooler
- Coolant flow problem through the cooler
- Fault in related temperature sensing or wiring
Symptoms
- Check engine light on
- Possible reduced power or rough running
How to diagnose it
- Check freeze-frame data and related EGR, coolant, and temperature-sensor codes to see the conditions when cooler B efficiency fell below the threshold.
- Inspect EGR cooler B, its coolant connections, and nearby hoses for leaks, damage, or signs of restricted coolant flow.
- Check coolant level and look for evidence of a cooling-system fault that could reduce flow through EGR cooler B.
- Inspect the temperature sensors associated with cooler B and their wiring for loose connectors, corrosion, or heat damage.
- Compare the cooler B temperature readings and test coolant flow or cooler operation using the manufacturer's specifications and service procedure.
Common fixes
- Repair a coolant leak or restore restricted coolant flow through EGR cooler B.
- Repair damaged wiring or connectors for the cooler B temperature sensors.
- Replace a confirmed faulty temperature sensor associated with cooler B.
- Clean or replace EGR cooler B if testing confirms restricted flow or inadequate heat transfer.
Can I keep driving?
If the engine runs normally and coolant temperature stays normal, drive gently and arrange prompt diagnosis; avoid heavy loads if power is reduced. Stop if the engine overheats, runs very roughly, or loses substantial power, since continued operation can worsen engine or emissions-system 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.