I have a 2002 Octavia 1.9 TDi. Starting wasn't a problem until Monday of this week.

Symptoms:

1. engine turns over but doesn't fire up
   
2. noticable that pre-heat (glowplug) light is not showing on dash (it's cold at the moment so I'd expect something)

Checks done:

1. multimeter between glowplug and lead - no current
   
2. battery fully charged and voltage checked (>11.5v)
   
3. sprayed wd40 on wire connections
   
4. fuses (facia and battery areas) checked OK
   
5. tried with spare key - still no start
   
6. Witnessed fuel flowing through clear fuel feed pipe after ignition turned
   
7. (seemingly) no other problems

Other info:

I charged battery yesterday and put back in car at at about 16:00. Car started (with a little trouble initially) . Tried shortly again afterwards and car started OK (and saw pre-heat light on the dashboard). Tried again this morning and car wouldn't start

My thoughts:

• car has started and it may be temp thing. My understanding is that below about 4 degrees C glowplugs are necessary since insufficient heat generated through compression. This would explain non start in cold and start in late afternoon with a fully charged battery
  
• no current to glowplugs when I would expect to see one leads me to believe that the issue is possibly:
  • coolant temp sensor
    
  • relay
    
  • wiring

I've been reading past threads which have been helpful, but I've been left with the following question -

1. How do I check whether the coolant temp sensor is working?
   
2. If the relay is failing, wouldn't that affect other things as well?
   
3. Can someone confirm which relay is used by the glowplugs?
   
4. How can you test a relay?
   
5. Wiring - eek any ideas?

I've got the car booked in to the dealers but they couldn't see me until next week and I've been quoted in excess of £120 to get the car there :eek:

HELP!

Many thanks

Mark

Try to start it with the engine coolant temperature sensor disconnected.

Relay

it could be relay 109 above the brake pedals, check the glow plugs for resistance by removing the large plastic cover to expose the glow plugs which are fed with a solid black plastic loom, pull this off all the plugs and check each plug they should be around 0.7 ohms each, they don't recieve power untill the temp drops below +7deg, have a look inside relay 109 (prise sides apart with small screwdriver) the contacts could be pitted or it could have a dry joint inside, to test a relay you put 12v across the coil and it shoud actuate by clicking,wouldn't have thought it would be the wiring unless its damaged someware,might be worth buying a relay or temp sensor and fitting them to see if it then starts, Halfords do have the glow plugs in if yours are faulty. I think if you unplug the temp sensor it fires up the relay / glow plugs as a test. hope you sort it - Stuart.

I thought that relay 109 operates many things other than the glow system so alot of other components would not work either as it is the main power relay for the car.There is a thread on here about it.I think there is a modified later type?

Check your multimeter on another battery 11.5 volts is way too low, a fully charged battery should be at least 13.2 volts, you may have a dead cell in the battery.

Apologies in the delay - but am sending this in the hope that it might help someone else.

Had the car towed to a local garage who diagnosed faulty wiring. Apparently it had been nipped (or something to that effect). Wiring fixed and (this) problem solved.

As for the others, see other posts...

Mark