What it means
The control module detected a range or performance fault in the diesel intake air flow control circuit.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The diesel intake air flow control circuit carries the position or control signal for the intake flap. P02E8 sets when that signal is outside the expected range or does not track system operation; the listed causes point to a short to ground, corroded connector pins, or insulation chafed through on the harness.
Common causes
Most likely first.
- Short to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
Symptoms
- Reduced engine power or slower acceleration
- Rough or uneven engine response
- Poorer fuel economy
How to diagnose it
- Review freeze-frame and live intake flow control data to identify whether the reported signal is out of range all the time or changes with flap movement.
- Inspect the intake flow control connector and harness for corrosion, exposed conductors, or chafing where the loom touches nearby parts.
- Check the signal circuit for a short to ground and inspect its ground and connector paths using the manufacturer's wiring information.
- Wiggle the harness while monitoring live data to locate a signal change caused by a damaged or poorly connected section.
- If the wiring checks out, test the sensor and actuator response against the manufacturer's specifications.
Common fixes
- Clean or repair corroded connector pins.
- Repair chafed wiring and restore insulation or harness routing.
- Repair a signal circuit short to ground.
- Replace a sensor or actuator only if circuit and component tests identify it as faulty.
Can I keep driving?
A short, gentle drive may be possible if the engine remains stable, but reduced power or uneven response can affect merging and overtaking. Avoid demanding acceleration and stop if it stalls or loses substantial power.
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.