P1621 2012 Partner

[AMacdonald]

Hi all.
My reliable old 2012 Partner HDi has decided to become less reliable. It has recently started throwing P1621 errors and dropping into limp mode very regularly. According to my reader the error is "Control Unit. Software Redundancy Fault At The Injection. Safety Level 2". My first thought (based on "Software Redundancy Fault" and some basic research) was a firmware or memory error in the ECU so I packed it off to ECUConnection for their plug-and-play replacement service. The replacement unit arrived back yesterday and I installed it today but the fault remains.

I'm wondering (and I'll ask them) if they copied the entire firmware from my old unit to the replacement or just the relevant stored config. If it's the latter, does anyone have any suggestions about where to look next? I have Lexia kicking around somewhere but I haven't used it much so it may take me a while to get useful information out of it.
Thanks
Angus

[mickthemaverick]

You may find a read through this site will give you an idea or two: https://www.engine-codes.com/p1621.html

[AMacdonald]

Thanks. The wiring all looks OK (but there is obviously a lot of it!) and the other suggestions on that site all relate to an internal ECU fault.

[AMacdonald]

Well, for the benefit of posterity and Googles future search results, the source of the trouble turned out to be the fuel rail pressure sensor. I remembered a single instance of P0192 a couple of weeks ago that vanished with a code clear. One new sensor and most of the skin on my right hand later (that thing is a bitch to access) and all now appears well. It was a good opportunity to remove the well established ecosystem of decomposed leaves under the windscreen scuttle panel too.

[mickthemaverick]

Well done and thanks for posting your solution.