Octavia fuse f34 keeps blowing.

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My 2002 Octavia fuse f34 keeps blowing and the epc light comes on. When I replace the fuse the epc light goes off and all is good for a few days. Then the epc will suddenly come back on and when I check the fuse has blown again. Any ideas where to start please?

[kentphil1]

What model octavia do you have?.

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What model octavia do you have?.

Hi, its the mk1.

[kentphil1]

Sorry, I meant is it diesel,petrol?, also is it a VRs, L&K , other trim variant?, also, is it manual or auto?, hatch or estate?

 

There are a lot of wiring diagrams for the mk1, and engine type and trim variant are quite important.

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Sorry, I meant is it diesel,petrol?, also is it a VRs, L&K , other trim variant?, also, is it manual or auto?, hatch or estate?

There are a lot of wiring diagrams for the mk1, and engine type and trim variant are quite important.

It's aa Skoda Octavia glx manual 1.4 litre petrol hatch.

[kentphil1]

It would help with an engine code - i.e BCA, AGU AUM etc to get more accurate info for you, but this is what I can find on limited info.

 

From the limited detail I have managed to get at the moment, that fuse would appear to be the feed for the ecu,

 

Have you checked the earths under the wiper cover are clean and bright and also that the drains for the plenum chamber are clear of leaves and general organic matter from trees etc?.

 

Also, have you had the car scanned for any codes that may be present yet?, as that may also be to your advantage.

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Have you checked the earths under the wiper cover are clean and bright and also that the drains for the plenum chamber are clear of leaves and general organic matter from trees etc?.

Also, have you had the car scanned for any codes that may be present yet?, as that may also be to your advantage.

Code I got was P0107.

I tried to get the wiper blades off before to have a look at the earths and they are stuck on I could not remove them.

[kentphil1]

That code relates to a map sensor fault, unless it is physically damaged or the loom to it is compromised physically, I'm not sure that they may be related.

 

Here is more info on that code - http://wiki.ross-tech.com/wiki/index.php/16491/P0107

 

I think you really need to get access under the wipers as soon as possible, as that is where all the wiring to that fuse emanates from and if the wipers are siezed, then it is quite likely that the area has not seen much attention in a while.

[webblade]

I think you really need to get access under the wipers as soon as possible, as that is where all the wiring to that fuse emanates from and if the wipers are siezed, then it is quite likely that the area has not seen much attention in a while.

OK thanks, I will try find a way to free them. Maybe some heat will do the trick.

[kentphil1]

You really should regard heat as a last resort as the arms are alloy and may melt or at least be damaged. you would be better using something like Plusgas, or in a push I have used cheap Coca Cola before now to dissolve the corrosion..

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I was able to remove the wipers and plastic tray to get to the ecu. The two earth wires looked to be reasonably good but I disconnected them anyway and gave them a good clean with light sandpaper and a spray of wd40. The ecu and all that compartment was dry and clean so I don't think water is getting in. I changed the fuse and it blew after a few hours. Could my map sensor be blowing the fuse?

[kentphil1]

The only simple way to tell really is to clear down the code, and wait for the fuse to blow and rescan, if the code has returned, it is possibly the sensor.

 

I must admit, I would be sceptical of the sensor unless it looks damaged, and would be more inclined to be looking for a short in the ecu supply cable, but you have not a lot to lose in checking the sensor first.

[webblade]

I must admit, I would be sceptical of the sensor unless it looks damaged, and would be more inclined to be looking for a short in the ecu supply cable, but you have not a lot to use in checking the sensor first.

You may be right about the ecu short as this has been going on a while and this is what happens - The epc light comes on and off intermittently and sometimes the engine management light comes on with it, and also turns off again which I didn't think was possible unless you clear the fault or remove the power supply but it just turns itself off? Also some other small things like door open light on dash staying on for days and then just turns off. The f34 fuse is for petrol/diesel management system and there are two more fuses for the same that have blown in the past. Do I just do a visual inspection of the ecu supply cables?

[kentphil1]

You will probably have to track the wiring back to each loom connector block in turn as you check for shorts with a multimeter unfortunately.

 

This is possibly going to be a bit of a trial, as this is an unusual fault that does not appear to have any obvious regular causes, as I did a google search to see if I could get any extra info for you.

[webblade]

You will probably have track the wiring back to each loom connector block in turn as you check for shorts with a multimeter unfortunately.

This is possibly going to be a bit of a trial, as this is an unusual fault that does not appear to have any obvious regular causes, as I did a google search to see if I could get any extra info for you.

OK kentphil1, thanks for all your help so far I appreciate it. I will try trace the fault with a multimeter over the weekend and let you know what happens.

[kentphil1]

Before you do that, I would double check that the sensor is not the cause, I did say it was unlikely, but it is still a small possibility. You may find loom damage or some piece of road debris near the sensor, it costs nothing but time and another fuse to rule it out really.

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Before you do that, I would double check that the sensor is not the cause, I did say it was unlikely, but it is still a small possibility. You may find loom damage or some piece of road debris near the sensor, it costs nothing but time and another fuse to rule it out really.

I'll do that first then, thanks.