Hi There, and first I'd like to thank your forum (and others) for helping myself and my dad fit both parking sensors and cruise control to my polo and diagnose all manner of faults/tweaks on it.

The fault on my polo is intermittent, and almost always follows a day of heavy rain, basically the steering light illuminates (wile driving or manuvering) and the power steering becomes heavy. Once this is triggered the next time the car starts the power steering may not start at all, and by switching it on and off a few times it'll eventually engage (with or without light and heavy steering).

Our local VW garage identified it (with my persistence it was water ingress) that the connections of the pump and loom have water ingress and have had corrosion. Price to replace both the pump and the loom at about £1140 fitted!

£1140 is a fair bit more than I'd like to spend, and I believe between my dad and I we have the skills to fix this ourselves, or at the least buy the parts for a local garage to fit for a lot less!

The technical bits:

I have a VCDS system and the fault is diagnosed (and agreed by the VW garage) as a short to ground, although currently its reset I believe it was on the reference voltage, when it reappears I'll post the exact fault.

The controller is identified as:

6R0423156A

Questions:

1.If I was to buy a replacement, can it be of a slightly different part number ie.6Q0423156? If so is this a direct drop in replacement or does it need some complex calibration?

Suggested replacement parts:

New: http://www.ebay.co.uk/itm/TRW-POWER-STEERING-PUMP-6R0423156-6Q0423156-VW-POLO-LUPO-IBIZA-SKODA-FABIA-NEW-/200973776369?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item2ecaf875f1

Different Part no:http://www.ebay.co.uk/itm/VW-POLO-1-2-ELECTRIC-POWER-STEERING-PUMP-6Q0423156M-6Q1423051AD-6Q2423051R-/251360198249?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item3a863c3e69

2. The garage was adamant that both the loom and the pump needed replacing, I can't personally see why the loom should fail (its just wires isnt it?) and might just need some tape to check its all sealed against water, to be honest the pump itself might still be ok and just need better water protection, what do you think?

3. Are there any service manuals/forum guides on the best way to access and replace the pump?

Sorry for the long post and I hope its all in the right place, thanks in advance for the help.

Not sure on question 1+2 but I believe the steering pump can be accessed by removing the front bumper. It's down near the washer bottle and horn so I'd guess that would be best. Don't know what the whole job entails but I reckon if I were you I'd look at replacing the pump myself and then if that fails get the replacement loom.

If this only happens after rain and then runs OK when it is dry, I suspect that the pump is probably quite all right, otherwise it would give permanent problems.

I would suggest removing and checking all of the multi-plugs that connect the system up, chances are that this is where the water is affecting the connections - as you say yourself, the loom is just wire, so providing that there are no breaks in it, that SHOULD be OK .

Regards.

I'll second the above,take a hair-dryer to it and then give it a liberal spray with silicone grease...

John

I tried everything at the time and in the end the pump itself needed replacing and handed it to an expert. Replaced both the sensor and motor just in case. The sensor was replaced first and didn't solve the problem so for future readers you'll probably just need to replace the motor, sadly the most expensive bit!