VW Golf MK5 2.0 GT TDI (BKD) G62 Engine Coolant Temp Sensor

[dk92]

Quick update. I noticed the temp gauge is stable when the car isn’t started and has the ignition on. So I took readings on my multimeter when the car was started

As I posted above the sensor gets a good stable voltage (55) when the ignition is on

However, when the engine runs the voltage runsat 555 on my reader which is about 5.5v which seems normal and then cuts to 0, then back to 5.5v, then 0 etc



Would this confirm it is the ECU or would it be a wiring/electrical fault with it dropping out ?

[dk92]

Car has been driven from the gym to the supermarket (3/4 mins) Dash temp consistent and just above the 50 deg mark, which is similar to what the app shows. Top pic and bottom is car with ignition on, until it goes all over the place when I literally start & run the car. Could this be an alternator issue?

[Crasher]

Check the ECU earths on the chassis leg behind the left headlight

[dk92]

Thanks mate. Had a go, wasn’t sure which one was the ecu ground so looked at both in the top pic. Found this bad wire connection in the fuse box (second pic) 3rd pic shows which wire it is.
However, since putting it all back together it now doesn’t turn over on the key at all m.Fault code and it’s saying the ecu is getting no power

What fun

[Crasher]

That’s the main power feed, I can’t help much more than that as I am in A&E with chest pains

[dk92]

That’s the main power feed, I can’t help much more than that as I am in A&E with chest pains

I’ll replace as soon as, probably causing the non turn over issue I’d imagine.

Jesus! Hope you’re alright fella! Quick recovery

[dk92]

Quick update and it’s good news. The problem has been sorted no engine check light and the car data (below) is steady, with the temp on the dash behaving normally.

I changed both sensors and the thermostat which had no impact as it was still misbehaving.

Roughly 4 days after this, I’d replaced my oil dipstick tube as it had snapped. I had to remove the rad switch next to the thermostat. On removing this, a small amount of coolant was lost as the stat wasn’t removed so kept all of the coolant in the block. Since replugging it back in it’s behaved normally.

Air in the system is the explanation I’m thinking?

Anyway hope this helps someone.
Cheers

[Crasher]

Jesus! Hope you’re alright fella! Quick recovery

I spent seven hours in a sweltering waiting room with hundreds of other people waiting in vein to see a doctor and at 11pm I gave up and signed myself out. I think I had cracked a rib but no idea how! Vodka helps.