Citroen Xsara Picasso wiring loom corroded where it meets ecu multiplug

Car: Citroen Xsara Picasso
Variant: Desire 2 (1.6) manual
Model Year: 2004
Categories: Leaks & Noises
My engine ECU, multiplug and wiring loom have water damage. I'm advised that the cause is a pressurised leak from the temp sensor unit, and that water has travelled a LONG way 'up' inside the copper wiring on the loom to where it meets the ECU.

They also advise that the temp sensor, the ECU & the wiring loom need replacing.

They can't see any leak, nor prove that it's from the temperature sensor (they just say that's the general reckoning) and

They also say it's not worth trying to keep existing loom by paring back / cleaning up the corroded wires.

I had a v bad experience with this dealership previously so seeking assurance that they're not pulling a fast one on me.

Questions:

CAN water leak upwards from the temp sensor and corrode the wiring all the way along to the ECU point?

Or is it likelier that the leak is water ingress from an inadequate ECU plug protective cover? (in which case it would be better to try and fix existing loom rather than replace)

Speedy advice appreciated!
Thanks.
Posted: Jun 24, 2011 (13 years ago)
Get a second opinion .If the temp sensor isn't leaking , how can it be the fault ?
Posted Jun 24, 2011 (13 years ago)
yes unfortunately this can happen. Check the plug at the coolant thermistor if it is corroded and the inside of the sensor has coolant in it then this is the cause. The coolant travels along the loom due to capillary action. The result is coolant inthe engine management ecu which usually means a new loom and ecu and temp sensor.
Posted Jun 24, 2011 (13 years ago)
Take " paulieone's " advice .He knows more about this than I do and has came across it before .Also good explanation of cause .
Posted Jun 24, 2011 (13 years ago)
Hi Paulieone,

Many thanks for your advice.

Do you mean they should (simply?) have been able to unplug something at the thermistor end and show me corrosion there too?

Because whilst they showed me corrosion where the multiplug meets the ECU, they weren't able to show me any corrosion at the temp sensor end, and implied there was no way of even checking for corrosion at that end. They certainly didn't mention having unplugged anything and 'seen' any coolant. And I couldn't see anything looking corroded where the wiring loom cable exited the temp sensor.

Is there any other possible cause of the problem?
We're likely going to have to scrap the car under the new ECU/LOOM/TEMP SENSOR scenario, so I need to be sure they're not trying it on.

Thanks again! No more questions, promise!!
Jane.
Posted Jun 29, 2011 (13 years ago)

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