Low Voltage Battery/ errors.

[Hamster67]

A month ago my van was struggling to start, I tested the battery and it did indeed need replaced.

Since that time I have been getting random errors, coolant temp sensors, camshaft pos sensor.

I have replaced the battery and the 3 sensors, reset the faults via carista but they returned.

I had left the van at my local garage to look at the timing, EGR and coolant but they now seem to think the problem is more likely electrical.

Have anyone experienced issues after running on a low voltage battery?

 

[Dellmassive]

possibly a wire problem,?

maybe corroded or rubbed through?

if the faults are clearing but returning then there is something wrong.

it may not be the sensor its self . . but the feed wires.


what year / spec van?


did you change sensors or a garage?

what was the other garage findings?

 

[Hamster67]

The van is a 2018 2.0tdi 102bhp 5 speed manual.

The garage changed the sensors.

Other finding was a strong smell of urea from the coolant, the level was fine.

Other than an occasional lumpy start, the only visible sign is the coolant temp would randomly sweep to 130° even from a cold start, and the fan would come on.

It happened when driving, I pulled over to check the level which was OK, and when I started the engine again it returned to 90 and I drove the 8 miles home, no issues.

The engine oil had only reached 63° when this happened so I doubt the reading is correct.

The coolant gauge then stopped working altogether putting the EML on just before I left it back to the garage.

 

[Dellmassive]

yeh, sound like somethings is going on here?

a rubbed through wire in the loom somewhere?

a good VCDS scan show any sensor wires with odd readings or wire shorts to ground etc?

any access to VCDS?

 

[Hamster67]

No just a carista, can the VCDS give more detail?

The garage themselves think it is electrical now, so hopefully they are heading in the right direction.

There is now a start/stop error on start up and info on here suggests a rubbed through wire at the loom as a possible cause for that.

Can you recommend a good VCDS ?

I thought the carista was the same thing/ different name.

 

[Dellmassive]

VCDS is the VW specific factory level diagnostics. (pricey)



Carista is generic with some VW stuff: (cheap)



TECH:

• Carista - How I Done It -
• Vcds / Vagcom - How I Done It -

 

[Hamster67]

So I had a VCDS scan done (£60) and it showed a coolant temp error that did not show up on my carista, manufacturer specific fault.

I couldn't clear it with the carista either but a capacitive discharge ( guided by @Dellmassive thread) cleared it.

I had the timing belt changed ( for peace of mind) after 10k and the garage discounted £100.

So I'm back in the road, the only fault that persists is the heater only blows cold air.

All these problems started at the exact time the battery was about to fail, so check your battery!

I