I have here a Polo 2011 MY with 1.2 TDI CFWA engine. It was a non-start, there were EGR blockages and injector problems so the engine came out to replace EGR valve & cooler, turbocharger has been replaced and the injectors have been replaced and coded / adapted. DPF has also been removed and cleaned.
The engine started after being reinstalled but error code P0088, fuel pressure too high is logged within 5 to 10 seconds of starting. I have checked fuel pressure on the supply side (5 bar measured), the return line is free and both filters have been replaced. I have checked and replaced IMV on the HP pump, the PRV on the rail and the rail pressure sensor as a last resort (and liaising with diesel specialists).
I have opened the old filter and there are no metal flakes or signs of pump failure (more likely to give P0087 anyhow) and all live supplies and wiring integrity have been checked / verified.
On checking rail pressure on the signal wire of rail pressure sensor it climbs to 600b then drops to 250b then climbs again in a cycle. I have reset the IMV and PRV setting in Basic Settings to no avail.
Is there a Rail Pressure sensor adaption please or do I need long coding for this (if so is there a code please?). Alternatively is there a VW sw update to overcome this issue?
To be clear the engine now runs, logs P0088 and runs lumpy, stuttering at idle but not cutting out. Revving to 3000 rpm the engine sounds fine but rail pressure cycles by climbing and then releasing.
Any help or guidance much appreciated.
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