My 2002 1.9TDi PD 100bhp has started over revving when starting from cold.  Also the glow plug light stays on for about 8-10 secs, which given the reasonable temperatures at the minute seems a bit long. here is a video of it from a cold start

 

 

Coolant temp sensor maybe?

Gave it a scan with vag-com last night, coolant sensor error and the coolant temp was showing -30.5c, will swap it out and that should be it sorted.

Glad to have been of help. Emoticons do not work with my Ipad!

Edited 17 April, 201412 yr by Danny 57

OK, more issues!! I changed the green temp sensor, all was fine for a day or two and then the car stopped getting upto 90c when driving.. now the temp gauge isn't even moving.. anyone any suggestions?

Is the coolant sensor registering a value in vcds now? I'd take the car out for a run and log what is happening with vcds if I were you. Could be your thermostat is stuck open, but I would expect it to at least heat up a bit even if it doesn't reach 90 degrees if this is the case.

This is a good website for diagnosing issues with the 1.9 PD engine with vcds:

https://sites.google.com/site/1810martin/vcds-and-pd-tdi-engine-health-check

There are two coolant temperature sensors. If I remember right, the green one you changed at the back of the cylinder head, which talks to the computer and the blue one at the bottom of the cooling system near the right hand side of the radiator underneath - I think this is for the instrument cluster.

No. The coolant sensor at the back of the engine incorporates two thermistors (4 pins) - one for the engine ECU and one for the instrument panel. They have differing resistances. The earlier unreliable sensor has a black body and the later (slightly better) design has a green body.

 

The sensor at the bottom of the radiator is the cooling fan switch.

 

rotodiesel.

Cheers, I have ordered another green 4 pin sensor to see if it's a dud sensor, scanned with vag-com this morning and getting a code under instruments as below which won't clear..

 

01039 - Engine Coolant Temperature Sensor (G2) Possible Symptoms

• Difficulties with starting a cold engine.
• Starting the engine when engine is warmish or warm, idle rpm immediately is 1200 - 3000 rpm.
• RPM at idle is irregular.
• With all engine temperatures seldom idle rpm will vary between 900 - 1000 rpm.
• With engine warm (90 °C) the engine temperature suddenly drops (70 °C) and slowly comes back to 90 °C.
• Bad acceleration during warming up.
  • Diesel: an indication is extreme long time burning time of the glow indication light.

Possible Causes

• Wiring and/or connections faulty
• Engine Coolant Temperature Sensor (G2) faulty

Possible Solutions

• Check wiring and connections
• Check / Replace Engine Coolant Temperature Sensor (G2)

Special Notes

• In MY 1995-2002 (?) in Europe at VW-cars the G2/G62 had the bad reputation of breaking down often. The default G2/G62 is black and all replacements are green.

Is the coolant sensor registering a value in vcds now? I'd take the car out for a run and log what is happening with vcds if I were you. Could be your thermostat is stuck open, but I would expect it to at least heat up a bit even if it doesn't reach 90 degrees if this is the case.

This is a good website for diagnosing issues with the 1.9 PD engine with vcds:

https://sites.google.com/site/1810martin/vcds-and-pd-tdi-engine-health-check

 

Thanks, vag-com was showing coolant at 18c when I started the car this morning and continued to rise.. I replaced the thermostat a few months back with a genuine skoda item..

 

Thanks for the link, will have a nosey

Edited 1 May, 201412 yr by technics100

I ordered another green 4 pin sensor, fitted it and all is good. temp up to 90C and no error codes..

Edited 6 May, 201412 yr by technics100