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Yay, "antipollution fault" fun time again

P0402: Permanent Fault: EGR Measured Airflow Higher Than Recommended

Cleared the fault, reappears within a few seconds of the engine starting.

Correct me if I'm wrong, it's referring to higher than recommended airflow through the MAF, so this means the EGR is more "closed" than it should be? The vac system appears fine, and I've tried switching the EGR E/V for a known good one - no improvement.

The two things that spring to mind are 1) a leak in the EGR circuit or 2) EGR valve stuck closed. On visual inspection I can't see any leaks at the EGR outlet or inlet. Is there any way of checking whether the valve is opening and closing properly?

Any other potential causes for this?

Thanks

Sounds to me like it would be a lot more straight forward to re-map and blank the thing. If you still get the error try a new MAF?

Yes I had thought of that Gareth, but I'd quite like to fix it if it's easy/cheap/possible. Otherwise blanking it shall be!

Good point on the MAF sensor, I'll try swapping this out with the one on the Coupe

That's strange because although EGR blanking/disabling causes fault codes these codes don't (normally?!) cause EMP/aunty P.

Jon, that's the fault I had after fitting a blanking plate / removing the air dosers and not changing the map to reflect the lack of EGR.

In my case, the engine ecu logged this as a temporary fault - no EML or Antipollution Fault messages.

It's possible your egr is failing to open, or maybe the intercooler to inlet manifold throttle body is stuck fully open. (Don't know which way it defaults with no vacuum to the capsule).

The odd thing is why does yours complain about this when many people seem to be able to blank the egr without any obvious sign of ecu dissatisfaction?

You may have to bite the bullet and install some more 'motivational' software.

Thanks Rich & Eric

I unplugged the MAF sensor, cleared the fault codes, plugged it back in and took it for a drive. The fault code still appears but so far no EML/anti-P warning.

I do think there's something up with the EGR but given that the car drives fine, I'm tempted to think it's stuck shut, and if so, it can stay like that

Will keep you updated if anything further presents itself...!