P245B: Exhaust Gas Recirculation Cooler Bypass Control Circuit Range/Performance Bank 1
What to do
This is worth attending to but rarely urgent. The car may run slightly rougher when cold or take longer to warm up, and the emissions system will not be working as intended.
Mention how the car behaves in the first few minutes from cold, since that is when the bypass does most of its work and when a fault here shows itself.
Ask whether the valve can be cleaned rather than replaced. Carbon build-up is the usual cause, these parts are expensive, and a valve that frees up and holds position afterwards has been genuinely repaired.
Short journeys make this worse. If most of your driving is a few miles at a time, an occasional longer run helps keep the whole exhaust gas recirculation system from coking up.
What this code means
The valve that routes exhaust gas around the EGR cooler is not moving the way the module commanded.
The bypass exists because recirculated exhaust gas is not always wanted cold. On a warm engine it is cooled before being fed back in, which lowers combustion temperature and suppresses the formation of nitrogen oxides. On a cold engine the opposite is useful — hot gas routed straight past the cooler helps the engine and the catalyst reach operating temperature faster.
Range/performance means the valve responded, but not correctly. It moved too slowly, stopped short of the commanded position, or the temperature downstream did not change in the way a working bypass would have produced. This is distinct from an open or shorted circuit, which sets a different code and is usually easier to find.
Carbon is the reason, most of the time. This valve sits directly in the exhaust stream, and soot builds up on the flap and its spindle until the mechanism binds. A valve that is merely sticky sets this code intermittently and cleanly for a while afterwards if it is freed, which is worth knowing before a new one is fitted.
Note that the fault may be thermal rather than mechanical. The module often infers bypass position from the coolant or gas temperature it expects to see, so a faulty temperature sensor produces this code with a perfectly good valve.
Likely causes
Start here
- Carbon build-up in the EGR system · moderate
- Seized EGR cooler bypass flap · moderate
Less common
- Faulty EGR cooler bypass valve · moderate
- Faulty coolant temperature sensor · easy
- Vacuum leak in the control circuit · moderate
Symptoms
Components involved
Information, not instruction
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Community experience
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