Hello all,
I have the above vehicle in from another garage who has replaced the egr valve twice, first one non genuine, then a genuine one, because of fault code P0402 EGR FLOW TOO HIGH(EXCESSIVE) & the fault still reappears. I have checked for leaks & found none, the EGR valve appears to operate correctly when actuated, but when trying to perform EGR flow adaptions the egr doesn't operate & fails the adaption test.I have removed the EGR valve & checked it & cleaned the throttle body & reset adaptions etc.
I should be able to find what's going on, because I currently have a VW Golf 1600 16v AZD engine code with the same management system , which I have been able to scope to compare with the Seat.
I think that there must be a fault with the control module, but would like some advice/comments on the waveforms.

Blue trace = EGR position.
Red trace = Wideband sensor
Green Trace = TPS
Yellow trace MAP sensor

The first waveform is the VW Golf (which has another fault, but performs the EGR adaption/test ok with a pressure difference of 85 mbar).
The second waveform is the Seat, where the EGR position doesn't change (the waveform isn't quite positioned correctly, but on subsequent tests it definitely doesn't alter position).The lambda reaction is a bit different & slower, but everything else appears ok.


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Kind regards,Andrew