The wife's Fabia 1.4 mpi is getting a few too many electrical problems at the moment so it's time to start seeking solutions.

I've done a scan with VCDS and the only relevant fault code is 'under voltage' (I'll get full details later).

Two major issues: coolant warning light and random locking activation.

Coolant warning light has been intermittent for a while but has twice come on and stayed on for a couple of days.

On both occasions, no new fault codes.

Coolant level looks OK with no signs of loss. Slight sludging but not getting worse. Oil filler cps is clear of sludge. This sludge in the coolant reservoir could be left over from a head gasket change 18 months ago.

I've no ideas on this one so I'm hoping someone here has.

The random door locking is also sporadic and appears to be mostly related to the passenger door where banging the door shut causes the central locking to activate/deactivate.

It has been known to lock/unlock several times whilst driving along.

I suspect that it may be a worn wire between the door and car which I am going to check tomorrow.

The central locking also only works from the key in the lock and not remotely. The key fob seems to use batteries very quickly and fails within months of a new battery being out in. This may not be relevant though.

Any other suggestions of where to look?

I've checked all the fuses and looked in the engine bay for any damaged wires, but nothing showing.

Any help appreciated.

The coolant level sensor, if that's the one you mean, is a very common issue. To replace it you need to buy a new header tank (should be ~£15) which will fix your issue.

 

The locking issue could be the micro switch in the door, I've not experienced this myself but read about it on here so no doubt there will be more info on it if you dig around a little.

An "under voltage" fault could be the sprague clutch on the alternator allowing it to slip when it should be under drive. The only check I can come up with for that is to observe whether or not the alternator is turning at the same speed as its drive pulley with the engine being accelerated.

 

Matt is probably right about the coolant level sensor, but cleaning the prongs in the expansion bottle with a flat screwdriver is quicker and even cheaper than buying a new header tank.

 

The locking issue might be the driver's door switch, or the associated wiring loom. This means taking off the door card and looking for corrosion in the contacts.

Thanks guys.

I put a new header tank in when I changed the head gasket, so it shouldn't be that after only 18 months!

I know about the possible micro switch issue (usually with Octavia Mk1's but had it on my Mk2) but this behaviour doesn't match. Hence why I suspect wiring fat in the loom between the door and car.

I'll have a closer look at the coolant prongs and pull the rubber collars between door and car open to see what I can see.

It's most likely the electrodes in the coolant reservoir, but test the coolant pump to be sure it's working. Remove the cap and check you have a steady stream of coolant returning to the reservoir when you raise the revs to about 3000.

What's the year/engine code/trim level?

It's a Fabia Classic 2003 6Y2 engine AQW.

I'll look at that tomorrow along with the other suggestions.

It's a Fabia Classic 2003 6Y2 engine AQW.

I'll look at that tomorrow along with the other suggestions.

On this car it is just as likely to be a wire between the door and the pillar as a microswitch, as the 'intelligence' is in the CCU.

Use a metal bar or screwdriver on the lock catcth to make the system see the door as closed when in fact it is still open. With the door open, manipulate the wires.

but cleaning the prongs in the expansion bottle with a flat screwdriver is quicker and even cheaper than buying a new header tank.

 

 

 

Unfortunately you can't get into it to do that. There is plastic in the way inside the neck.

Bit of an update on the coolant / warning light - it appears that the light has been coming on more regularly and has been on most of today. And it's red!

 

Coolant and the expansion tank has quite rapidly gone from pink with a tiny sludge residue to brown stained tank and darker coolant but with only a slight increase in the amount of sludge. But this has developed quite quickly (about 2 weeks since I last looked).

 

I suspect that oil is leaking into the coolant in small quantities (the oil is still where I last checked it at half way up the dipstick marks), but there is no sign that coolant is leaking into oil (at least that is an improvement since I fitted new head gaskets and cylinder head...)

 

I'm ordering a new expansion tank and coolant and will do an oil and filter change as well (I have these in the garage anyway and it appears to be due as the service indicator is flashing 'OIL') when they arrive.

 

I'll check the electrical gremlins associated with the central locking tomorrow and be in SWMBO's good books if I can fix that...

Updates:

 

No sign of any damage to the wires running form the doors to the car.

 

I've not taken the door cards off as I scanned it with VCDS and neither the driver's nor passenger's door register as being open whereas the two rear doors do.

 

To me this suggests the issue is somewhere else as to have both doors go within a few months of each other seems too improbable.

 

There's no damage to the fuses or cables from the battery and the cables are seated well on the battery. There is a small nick in the cover of the black / negative cable coming from the fuses on top of the battery down the front of the car. It has exposed the cables inside but is not in contact with any metal parts. No sign of damage to the copper strands other than a small tarnished patch.

 

Given that the car is worth less than £1000 if it was in good condition and all working properly, I feel like giving in and buying another vehicle for SWMBO. But I know I'd be in a whole heap of trouble for that...

Did you check the wires back to connector behind the 'A' pillar trims? Those connectors are prone to corrosion.

No, I didn't. But I will.

Which cables would run up the A pillars in a 'Classic' spec Fabia?

All the central locking wiring passes through connectors behind the lower 'A' pillar trims

Just to clarify... I'm talking about the lower 'A' pillar trims and the connectors behind are at floor level.

Now I understand. Thanks for clarifying.

I'll take a look.

Just wondering if this could be a case of a failing central electric module?

What's the likelihood of that happening and causing these issues (both drivers door locks, stereo not functioning & coolant light)?

Just wondering if this could be a case of a failing central electric module?

What's the likelihood of that happening and causing these issues (both drivers door locks, stereo not functioning & coolant light)?

It could be. There is a CCU but the 4 power feeds for the door switch logic come from the CECM.

When I scan the car, I get a central electrics mode (is that what you mean by the CECM?) but I can't get any other relevant modules to show or scan (central locking, for example).

I'm going to have a look at the workshop manuals and parts catalogues later to see if I can find out where these are and whether I have both.