High idle and fans running. Electrical?

[LC_Tom]

Hi all I wonder if anybody could help me as I’m at a loss here.
Recently purchased a mk3 seat Leon and it has idle (1000rpm) and the fans stay running for a few minutes after engine is switched off.
have had the DPF Regened and a chemical clean through it by a mechanic and also the DPF Sensor changed. Have taken it on plenty of long journeys to see if it helps but nothing! Shows no fault codes??
Engine stop/start function doesn’t work it says power consumption is high? Mechanic is now suggesting an electrical issue which is raising the idle and causing the fans to come on. Has anybody got any ideas or been through similar? Don’t want to throw more money at it as I haven’t had it long. Any advice would be greatly appreciated

 

[Ashb14]

The engine will idle at 1k when it is cold/warming, this should go away as the engine reaches optimal temp, if this is the case it's completely normal.

The fans will often stay on for a few minutes after you have switched it off, this is also normal. If the engine needs cooling, it still needs cooling even if you have switched it off. I would say check for air pockets, leaks and check the quality and level of coolant if you want to be sure, but I assume this was the first thing the mechanic did.

 

[LC_Tom]

Thank your reply mate means a lot. Even after a long journey the idle will sit at 1000 and the fans will be blaring for a few minutes after shut off. The occasional time the revs have been normal and I’ve turned the car off and no fans or anything.., now the winter is coming I don’t want my battery to die. It says power consumption is high will that be causing the revs to sit higher and fans to stay on mate?

 

[Ashb14]

Thank your reply mate means a lot. Even after a long journey the idle will sit at 1000 and the fans will be blaring for a few minutes after shut off. The occasional time the revs have been normal and I’ve turned the car off and no fans or anything.., now the winter is coming I don’t want my battery to die. It says power consumption is high will that be causing the revs to sit higher and fans to stay on mate?

Yeah mate no worries on the fans there. The power consumption being high isn't really to do with any issues on the car either, the power consumption will be high based on things like driving mode (eco, normal, sport), how much you use the air-con, if your lights are on, radio etc. I have always had a high power consumption in the 4 years I have owned mine, it is just because I drive in sport mode with the air-con on all the time.

You mentioned the stop-start doesn't work, so the first thing I would do is check the battery and alternator. Check that the battery is actually a stop-start battery and get a health check done on it. You can test the alternator by removing the negative terminal from the battery while the car is running, if it stays running your alternator is fine, if the car cuts out you need a new alternator.

As for the revs, if it still idles at 1000rpm while at optimal temp, then you may have a fuel or intake issue. I would start by putting some Redex diesel cleaner into the fuel system to clean the pump and injectors, drive it around for about 50-100 miles and see if it sorts it. I would also change the air filter if it has not been changed for a bit as it may restrict air flow to the engine, causing the car to choke and increase revs. Both cheap easy fixes if they work, if not I would then remove the injectors off the car completely to clean them. If you are still having issues, try changing the glow plugs if they haven't been changed for a while. If none of that helps then you may be looking at replacing sensors, it could be cam sensor, crank sensor, MAF sensor, MAP sensor etc. however, these issues are electrical faults so would usually throw up a fault code on a diagnostic scan as the car is unable to read the sensors data correctly. If none of that helps you may be looking at taking it to a dealer or specialist.

When was it last serviced? What's the mileage?

 

[LC_Tom]

As for the power consumption being high I’ve turned all lights off, heaters air con, radio etc and put it on driving mode normal and still seems to do it so not sure where the high consumption is. Brilliant thanks for the advice for the battery pal I can definitely get that checked out and see what happens.
I can buy some red ex and Chuck that through see if it works, I’d have thought over the weekend I put about 250 miles on it would of helped but it never, car runs fine in itself no issues just the high revs and fans coming and staying on is bugging me. Injectors are they expensive to check or replace? I’m not a mechanic or don’t know much so don’t know where to start all I know is that the car running high idle means it’s doing something and the fans staying on isn’t right lol, appreciate all your suggestions bud and I’ll see if I can get them checked. Apparently the dealership I bought it from took it a specialist to check all the car over and run diagnostics but recorded no faults and said it’s fine with no issues.

mileage is 158k last serviced at 156 in April

 

[LC_Tom]

Also forgot to mention if you turn the car off and then back on again the fans will go off and it’ll idle fine for a good 10 minutes and then start doing it again

 

[BillyCool]

The car will idle at 1000rpm if doing a DPF regen. If you switch it off during a regen, the fan will continue to run until it cools. It could be relevant.

The only way to know if it's doing a regen is to check. The best way (and a good way to check your DPF health) is to get an ODB dongle and the VAG DPF app.

This will allow you to see all of the DPF data and whether the high revs coincides with a DPF regen. This is what it looks like:

Normal DPF temp is around 200 degrees C. To do a regen it heats up to 550+. Ideally, you want to finish the regen before switching off. You can check how full your DPF is and how often it regens.

The Carista OBD dongle is really good:

AMAZON

Might be completely unrealated but it's quite a useful tool anyway and the dongle can be used with other software as well. Usually with Carista, you get 30 days free membership so you can do some basic mods as well if you want.

 

[LC_Tom]

The car will idle at 1000rpm if doing a DPF regen. If you switch it off during a regen, the fan will continue to run until it cools. It could be relevant.

The only way to know if it's doing a regen is to check. The best way (and a good way to check your DPF health) is to get an ODB dongle and the VAG DPF app.

This will allow you to see all of the DPF data and whether the high revs coincides with a DPF regen. This is what it looks like:

View attachment 45231

Normal DPF temp is around 200 degrees C. To do a regen it heats up to 550+. Ideally, you want to finish the regen before switching off. You can check how full your DPF is and how often it regens.

The Carista OBD dongle is really good:

AMAZON

Might be completely unrealated but it's quite a useful tool anyway and the dongle can be used with other software as well. Usually with Carista, you get 30 days free membership so you can do some basic mods as well if you want.

Hi billy thanks for the reply. I did think the high idle and fans running was for a Regen as did the guy working on my car, no matter how long you run the car for the idle and fans still stay running, did 100 miles at the weekend on the motorway still nothing. He reset the DPF and chemical cleaned it, the soot levels are low so not sure what’s going on it’s like it’s not stopping Regen if it is that. Could it be a faulty fan do you think? Or a temperature sensor or something, as I’ve said there isn’t any faults showing

 

[BillyCool]

Really can't say. Too many variables. Don't know how effective a DPF chemical clean is or what other factors can influence it.

I'd still want to run VAG DPF to see what info the car is getting from the DPF. It's almost like it's in permanent regen.

If the car thought the coolant temp was too high to run the fan I'm not sure why it would idle so high. No way to tell.

Could be a bad fan switch? I have replaced my coolant sensor on the engine block and the mechanic said it was a nightmare to do. I think there are actually 2 sensors. The problem with a bad sensor or switch is it won't necessarily throw up a fault code. My switchable water pump went stupid and never threw a code. Or my blocked heater matrix or my cr@ppy plastic cam cover. The list goes on!

I really would try the dongle and VAG DPT just to eliminate it. Either that or go and speak to a VAG master tech or someone who knows more about it. You can only self diagnose so much.

 

[LC_Tom]

Really can't say. Too many variables. Don't know how effective a DPF chemical clean is or what other factors can influence it.

I'd still want to run VAG DPF to see what info the car is getting from the DPF. It's almost like it's in permanent regen.

If the car thought the coolant temp was too high to run the fan I'm not sure why it would idle so high. No way to tell.

Could be a bad fan switch? I have replaced my coolant sensor on the engine block and the mechanic said it was a nightmare to do. I think there are actually 2 sensors. The problem with a bad sensor or switch is it won't necessarily throw up a fault code. My switchable water pump went stupid and never threw a code. Or my blocked heater matrix or my cr@ppy plastic cam cover. The list goes on!

I really would try the dongle and VAG DPT just to eliminate it. Either that or go and speak to a VAG master tech or someone who knows more about it. You can only self diagnose so much.

Thankyou mate I do appreciate that. Yeah it is a weird one that only seems to happen intermittently, stuck at the moment as to what it can be lol

 

[BillyCool]

Thankyou mate I do appreciate that. Yeah it is a weird one that only seems to happen intermittently, stuck at the moment as to what it can be lol

Today my car sat at 1000rpm sitting at traffic lights at the end of a 7 mile drive to work. I know it's to do with the stupid VAG `cold start` thing, almost like an autochoke. Only does it when the temp drops to around 4 or 5 degrees C or less. No idea why is feels the need to do it!

I can only reinforce monitoring your regens. It will give you a lot of data and help eliminate that as a possible cause. It almost feels like your car is trying to do a permanent regen.

 

[LC_Tom]

Today my car sat at 1000rpm sitting at traffic lights at the end of a 7 mile drive to work. I know it's to do with the stupid VAG `cold start` thing, almost like an autochoke. Only does it when the temp drops to around 4 or 5 degrees C or less. No idea why is feels the need to do it!

I can only reinforce monitoring your regens. It will give you a lot of data and help eliminate that as a possible cause. It almost feels like your car is trying to do a permanent regen.

I drove to work this morning pulled up in the car park and the idle was fine sat at 800rpm and the fans never came on or stayed on, first time it’s done that which is weird. When it does do it if you turn the car off and then back on it’ll idle normal and cut the fan off for a good 10 minutes and then start idling high and fans come on again. I will definitely monitor the Regen mate as I said the mechanic checked the soot levels they was low and ran chemical through it and it was all fine. Surely it can’t Regen all the time it’s like it’s stuck. I’m thinking and hoping maybe a faulty sensor or fan switch. As I said this morning fingers crossed it never happened, will have a good long motorway journey AGAIN tomorrow

 

[LC_Tom]

I drove to work this morning pulled up in the car park and the idle was fine sat at 800rpm and the fans never came on or stayed on, first time it’s done that which is weird. When it does do it if you turn the car off and then back on it’ll idle normal and cut the fan off for a good 10 minutes and then start idling high and fans come on again. I will definitely monitor the Regen mate as I said the mechanic checked the soot levels they was low and ran chemical through it and it was all fine. Surely it can’t Regen all the time it’s like it’s stuck. I’m thinking and hoping maybe a faulty sensor or fan switch. As I said this morning fingers crossed it never happened, will have a good long motorway journey AGAIN tomorrow

UPDATE: drove home from work, half way back I stopped at a set of traffic lights and noticed the idle high again, fans spinning when turned off for a few mins too. I’ve read a few threads and people have said there’s are the same and have been for a long time so I’m not sure if mine is normal for it to do that