P2391: Diesel Intake Air Flow B Control Performance
What to do
The early warning of a sticking valve — cleaning while it still moves beats replacing after it stops.
What this code means
The second intake air flow valve is not doing what it is told — circuit whole, response wrong, which in this family means one thing before all others: carbon. The valve lives where EGR soot meets oil vapour, the paste that results binds flaps and stiffens spindles, and a valve that lags its commands is a valve part-seized. The P2076 logic applies: this is the cheap early warning before the stuck codes arrive, and a cleaning now is the inexpensive version of the repair.
Likely causes
Start here
- Carbon-coated EGR throttle valve · moderate
Less common
- Failed EGR throttle actuator · moderate
- Corroded or loose connector · easy
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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