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Paulfitzg

Locate Octavia Glow Plug Relay

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I am trying to find where the glow plug relay is on a 2003/2004 skoda octavia - any ideas?

My problem is that the glow plug light comes on but goes off after a second even when the engine is cold. I have replaced the glow plugs and would like to try replacing the relay also.

Thanks

Paul.

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Assuming it's a mkI you need to remove the trim that is directly above the pedals on the underside of the dashboard, then if you look up into the dash you will see a number of relays - the glowplug relay should have 109 printed on it and it's probably grey. You should be able to reach up and remove it, note which way round it is fitted and replace with a new one.

Could also be a probelm with the coolant temperature sensor. Also at the moment it is nowhere near cold enough to make the glow plugs come on. You could try unplugging the CTS and see if the glow plug light stays on (should be about 20 secs with the CTS unplugged).

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Still having difficulty with this issue. I have tried the following;

1. Replaced glow plugs

2. Replaced relay 103 and 109

3. Removed cable from cooland tank

The problem still exists. When I turn the key the glow plug light comes on and goes off after about 2 seconds. It is not heating long enough so starting the car is difficult. Thanks for the help so far. Any more suggestions would be welcomed.

Regards

Paul.

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When you say cold, is it below 5 degC?

If not then the glowplug system should not operate and what you see is normal.

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When you say cold, is it below 5 degC?

If not then the glowplug system should not operate and what you see is normal.

It was below 5C this morning and the glow plug light still went out after 2 secs. If I disconnect the coolant sensor it goes out after 2 secs also.

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From memory, the tell-tale in the dash is fed from the glow-plug relay (180?), so if it was dead you wouldn't see a 2 second delay. It would go off at the same time as the other lights

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errr, yes it is!

109 is the main power relay for the engine ecu.

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Still having difficulty with this issue. I have tried the following;

1. Replaced glow plugs

2. Replaced relay 103 and 109

3. Removed cable from cooland tank

The problem still exists. When I turn the key the glow plug light comes on and goes off after about 2 seconds. It is not heating long enough so starting the car is difficult. Thanks for the help so far. Any more suggestions would be welcomed.

Regards

Paul.

Coolant temp sensor isn't in the header tank, that's the level sensor. The temp sensor is in the coolant hose above the gearbox.

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Coolant temp sensor isn't in the header tank, that's the level sensor. The temp sensor is in the coolant hose above the gearbox.

Sounds difficult to a access. Should I be able to get at this from the engine compartment or should I go at it from underneath.

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Still having problems unfortunately.

So far I have replaced the glow plugs, glow plug relay and coolant temperature sensor. The glow plug light still goes out almost immediately when i turn the key. Lots of difficulty starting in the mornings, have to turn key 5 or 6 times to get some heat into plugs.

I did notice that if I remove the cable from the CTS the glow plug light stays on for 10 second or so and car starts fine. Anyone got any ideas?

Thanks to everyone for the help so far.

Paul.

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Did you fit the correct coolant temp sensor?

Looks the same as the one I took out. Got it from main dealer who located it using the chasis number.

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Take a look inside the plug. Corroded contacts or crud between the contacts will cause the CTS to read high. The two wires go straight back to the ECU, so there isn't much more to check.

What was the actual temperature, when you tried to start the car? Was it below 5decC?

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Im probably betting there is nothing wrong and as yet its just not cold enough for the glow plugs to operate. You dont say what engine it is but tbh the glow plugs dont really do much. I suspect your difficult start is another issue.

Any fault codes?

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Still trying to resolve this issue unfortunately. The car is a Type 1U Octavia. I have replaced glow plug relay, glow plugs and coolant temp sensor. Glow plug light just stays on for about 1 second even though temperature is below freezing.

I am getting the following error from the computer

Address 01: Engine

Controller: 038 906 012 HA

Component: 1,9l R4 EDC 0000SG 4922

Coding: 00002

Shop # WSC 31480

17664 - Engine Coolant Temp Sensor (G62): Open or Short to Plus

P1256 - 35-00--

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That means the coolant temp sensor is open circuit or disconnected.

You changed the sensor down the side of the head so I'd make sure the plug is on properly. If it is then the wiring needs to be checked back to the ecu.

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That means the coolant temp sensor is open circuit or disconnected.

You changed the sensor down the side of the head so I'd make sure the plug is on properly. If it is then the wiring needs to be checked back to the ecu.

Thanks for the reply, Do I just check the cable for wear ant tear of is there a way to check using a multi meter?

Thanks

Paul

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Assuming you have done #16, you are probably looking for a short circuit or water ingress (probably at the ECU end).

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Open short to positive normally indicates a blown fuse or something open circuit.

If it's shorted to earth the wording changes, same with a resistive fault.

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Open short to positive normally indicates a blown fuse or something open circuit.

If it's shorted to earth the wording changes, same with a resistive fault.

TBH, I don't think OP's problem is due to the CTS or glowplugs. My guess is the fault code was logged when the CTS was unplugged as a test. Surely, if it is o/c, the glowplug light would be on for longer than one second.

I started my TDi (AHF) at -1.5degC without waiting for the glowplug light to go off (first cold morning - forgot to wait) and whilst there was a slight hesitation, it only took a second or so.

My guess would be another issue such as fuel pump timing.

Edited by rwbaldwin

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