Hi, I’ve recently bought a Skoda Octavia mklll. I am a taxi driver so do all manner of distances in the car but just in the last week I’ve noticed on the short runs around town when I’m sat in traffic the start/stop will stop working, the fans come on and I can smell burning. It seems to do this continuously until I get a longer run and can do some decent speed for a decent amount of time. Also it’s seems more sluggish when the fan is running and when I check under the bonnet it’s so hot that the bonnet stand is almost too hot to touch. Is this normal? 

I'm assuming it's a diesel.

 

It is but it’s not new and has only just started doing this every day now. Do you think it could be partially blocked? 

What's the age and mileage? 

It’s a 66 plate and done 88,000 miles. 

Don't panic for now, allow it to do its thing first, let the dpf regeneration complete if you can when doing short runs, it can take 10 minutes or so to run on especially at idle, If it gets interrupted then it will start again if doing short journeys again so just try and let it finish this process. 

 

My 16 plate has 94k miles on it and dpf regens every 250miles or so, however I drive it and it's always been like that. Just familiarise yourself with how often it does it.

 

Don't bother with "an Italian tune" or driving it in low gear at speed it won't do anything the car can care for the dpf automatically. 

 

If really worried you can get VAG Dpf app on a phone and a little Bluetooth device (Dongle) that plugs into the purple diagnostic socket under the driver side dash and you can see how the dpf is. Or find someone local with VCDS. 

Thanks for the advice! It seems to be running a lot longer than 10 minutes and everything feels very hot under the bonnet though, that’s my main concern. I bought this car about a month ago and have already had both water pumps replaced due to overheating so I’m very sensitive to anything else that could cause potential damage. The temp gauge has been solid 90 since the new main water pump was fitted and the oil fluctuates between 90 and 110 so it all seems fine but I feel really on edge about it. I’ve got no come back on the garage that sold me it either as I’m not classed as a consumer due to the fact I’m a taxi driver so classed as a business. 

11 hours ago, Dean17 said:

It’s a 66 plate and done 88,000 miles. 

 

So not especially low mileage for the age.  I would follow @paulski's advice initially.  Maybe turn stop/start off for a bit to ensure it keeps the hot flow through the system.  And maybe some good fuel, but this not necessarily confirmed to help.

If it keeps regenning more than you expect then a further investigation onto the state of the dpf is probably required.  As far as I've seen no generic additives can unblock a DPF.  To do that you need to remove it or replace it.

Ok thanks for the advice everyone. I’ve just thought, could running it on eco mode all the time make it regenerate more? I’m going to put it on normal for the day and see if that makes any difference. 

Certainly coolant temperature is operating as normal and oil temp looks to in spec between 90 and 110c. 

 

The heat needed to regen the DPF is circa 500C , don't be alarmed. There's heat shielding but hence the fans also run on for a good while if engine is switched off 

 

Not sure if VW tested one to destruction, with DPF regen at 500C,  stationary vehicle, no heat shielding and no fans operating that would make interesting YouTube video! 

Edited 20 September, 20232 yr by paulski

On my own car 2.0 TDI DSG, running ECO mode makes no difference to how the DPF regens operate, they don't happen any sooner or later from my experience. 

 

Regards

 

4 hours ago, MarkyG82 said:

 

 And maybe some good fuel, but this not necessarily confirmed to help.

 

Mine definately regens more when it hasn't got VPower in it

The first regen I had, as I recall, I had arrived home and parked on the drive. The engine was revving and the heat and smell was tremendous,

I thought the engine was on fire and ran the car back away from the house and shut down the engine! All was well but it finished off the regen

at the local roundabout engine revving and fumes  causing other cars to shun my vehicle. 

1 hour ago, gumdrop said:

The first regen I had, as I recall, I had arrived home and parked on the drive. The engine was revving and the heat and smell was tremendous,

I thought the engine was on fire and ran the car back away from the house and shut down the engine! All was well but it finished off the regen

at the local roundabout engine revving and fumes  causing other cars to shun my vehicle. 

When you say revving, how many rpm?  It should regen at a high idle speed of 1000 rpm.

Well I’ve driven it for the full day again and let it do it’s own thing, turned off start/stop for the most part and got it out for a good run so all seemed fine. At about 4 o’clock the bonnet seemed really hot and then it started stuttering when I was trying to accelerate. Fans on again full blast when I stopped and turned engine off. When I first bought it about 5 weeks ago it was overheating and the gauge was moving up and down and bleeping at me warning me to pull over. Had a new water pump fitted after the other only lasted about 2000 miles and it’s been ok with regards to the needle moving but it seems to be getting hotter now than it did with a faulty water pump to me. 

Mine regens after each 200...300km (in winter- more often). It takes exactly 20min and idle is 1000rpm. '2016 car with 155k km on clock.

@Dean17 I would take it to someone you trust with the gear (e.g. vcds) to look at the readouts. I think there are pressure sensors either side of the dpf. The dop in pressure should be within a certain range (needs looking up). If it's too high then it's probably blocked. My guess is the car was sold as the previous owner knew it was coming up to dpf replacement time. 

Brillaint. That’ll be at least a grand won’t it? 

4 hours ago, ords said:

When you say revving, how many rpm?  It should regen at a high idle speed of 1000 rpm.

I think it was around 1500rpm but it was back when the Yeti with Ad Blue first came out say 6-8years ago.

FWIW from memory my 1.6 will do approx. 1.5 regens to each tank of fuel.

Advice I've previously read (and follow) includes driving in a gear to maintain 1.5-2k rpm, once it starts (idle is at 1k rpm) it'll complete within 20 mins. Oddly the car will still start/stop during the procedure so although mine mostly doesn't work, I do turn the start/stop off when it's doing one. There is a data value you can watch if you have OBDeleven or VCDS that shows you how the regen is progressing (Ash %?)

 

As for "ECO" mode, I can get higher MPG driving everywhere in sport mode... ECO mode my behind!

Edited 21 September, 20232 yr by micro

10 hours ago, micro said:

 

 

As for "ECO" mode, I can get higher MPG driving everywhere in sport mode... ECO mode my behind!

I used to run my in ECO in town to get in a higher gear quickly and switch to normal on the open road as I felt more in control with engine braking etc. Now, it's in normal all the time with much the same economy and the gear shifts are the same. 

On 20/09/2023 at 18:46, MarkyG82 said:

@Dean17 I would take it to someone you trust with the gear (e.g. vcds) to look at the readouts. I think there are pressure sensors either side of the dpf. The dop in pressure should be within a certain range (needs looking up). If it's too high then it's probably blocked. My guess is the car was sold as the previous owner knew it was coming up to dpf replacement time. 

Fwiw, a 2016 car with 88k miles on it has "probably" not been sat around doing short trips all its life. 

 

With regard to diagnostics, VCDS (a tool that I have myself) will certainly show various parameters for the dpf. I check mine fairly often, it's the Ash soot level that is unburnt material that has a finite value when it requires replacement. At approx  86k miles mine was at 32grams, and a full ash soot level is reported to be 80grams. It is suggested that a dpf should generally last greater than 150k miles if not abused. 

 

 

12 minutes ago, paulski said:

Fwiw, a 2016 car with 88k miles on it has "probably" not been sat around doing short trips all its life. 

...

. It is suggested that a dpf should generally last greater than 150k miles if not abused. 

 

Could also have done all it's mileage pre COVID and only done short trips for the last 3 years.

 

Wild assumption time: had it not been used at the weekend the mileage equates to roughly 48 miles a day. You'd expect that sort of usage to be acceptable for dpf maintenance. I think there is still something potentially awry and a dig into the numbers might point a knowledgeable mechanic in the right direction.

The funny thing is I drove the car for 10 and a half hours straight except for a 20 minute stop over 500 miles the day after I bought it and it seemed absolutely fine. Then a week later after running very short runs around the town I did the same trip again and the same. A few days after that it started over heating. Got a new water pump fitted and it seems fine with regards to the instruments and computer but only now have I noticed the other problem. 
 

Got it booked in with a Vw specialist on Saturday morning anyway so hopefully he’ll shed some light on what’s going on with it. 

Just to update anyone who’s curious. I took my car to my local Skoda specialist who put it on the Vcsd and it said coolant pump c stuck. He said because it was an intermittent fault it wasn’t allowing the regen to complete so he wiped the fault off and put it into a forced regen as there was 23g of soot in the dpf and apparently if they go over 80 they can’t be regenerated after that. Seemed ok for the next week until I had coolant pump c replaced on Friday. 

However, it still seems to be going in to active regen too much to me. This morning about 9am the stop/start had stopped working, the engine had set itself to 1000 rpm and the fans came on. 10/20 minutes or so of this then the start/stop worked again. So I thought it’d finished, great that was a normal regen. But after working all day and sitting in bumper to bumper traffic and only doing about 50 miles it started doing it again at about 7pm. Only this time after 10/20 minutes of 1000rpm while idling it kept going to start/stop as if it had finished, then I would start the engine again and move up in the queue and it’d go back up to 1000rpm and say the start/stop was disabled again. I just don’t understand why it’s doing it so much. Long shot I know but had anybody else had this?