1.2 TSI EPC Error (P334a)

VeeFource

Active Member
Dec 5, 2014
121
2
Hi All,

Odd one this, haven't been able to find much info on it either. The car sometimes starts with the EPC light on accompanied by a "Stop Start Error" message on the MFD and goes into uber limp mode (25mph is an acheivement). Once it was also accompanied by the check engine light too, although this cleared itself after a few runs. VCDS recorded this (which is also why I knew it would be safe to carry on driving):

1 Fault Found:
10478 - Charge Pressure Control Actuator
P334A 00 [173] - Electrical Malfunction
MIL ON - Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 5
Mileage: 73898 km
Date: 2016.01.07
Time: 10:17:20

I did have to unplug this actuator when I changed the air filter for better access not long before I got this error but I've checked it's in properly a fair few times and have also cleaned it with contact cleaner for good measure. So it's either I've some how managed to disturb the loom into the plug (unlikely I'd have thought), or it's just a coincidence.

I'm pretty sure it isn't due any software updates as it looks to have the actuator shim that was fitted during the 2012 recall. The really wierd part though is the car runs totally fine as long as it starts ok without the light..

Anyone else had this before? Is it new actuator or dare I say it, new turbo time?

Thanks in advance!
 

Yorkie911

York
May 22, 2014
40
0
Surrey
I have a 61 plate 1.2 tsi and get the P334/P334a fault code and EPC light come on mine all the time when its cold. The first year I had the car it probably only happened once, second year only a handful of times and now it seems to happen roughly 2 or 3 times a month in winter(rarely if ever in summer). Mine always comes on about 10 seconds after the car is started followed by an immediate loss in all power (feels like it has 10bhp). Although it scared me at first, turning the engine off and on again clears the EPC light and the car immediately returns back to normal.

My car did have the recall in 2012 but I have a feeling that it never solved the problem entirely. From what I've managed to gather from online sources, as long as you aren't seeing the P334b code, you shouldn't really have much to worry about.

I have a diagnostics reader which gave me the same information you have above. My car has been remapped to 130hp for over a year now and this doesn't appear to have affected this issue.
 
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VeeFource

Active Member
Dec 5, 2014
121
2
Funnily enough my car does this exact thing and it feels like a misfire but without any noise. Since it started getting colder last year as it was going into winter it developed this issue. It concerns me quite a lot as it didn't do this for the first three years of ownership.

Normally it happens on about 50-80% throttle, within the first 5 minutes of the engine being on. I think it predominately happens in second gear but I know it can happen in any gear.

It rarely bucks once its warmed up. Sometimes it bucks twice, around a second after the first buck.
Just snipped the above from the bucking under acceleration thread as i'm thinking it's probably a bit too much of a coincidence we've both had these issues.

Ours also started doing the bucking thing in the cold weather but it stopped after I'd been driving around with the TC & ESP switched off for a while. I thought it was because the car needed to learn the new tyre setup as I'd rotated them just before it started happening as mentioned in that thread. But maybe it's to do with the actuator as this also started not long after (but I've not had the bucking thing since) and surely can't just be coincidence...

The only difference is on ours it could do both of these things even when the car is fully warm and had been driven a long time. But the fact they both started happening as the weather's cooled as well as yours did is very interesting.

I've since managed to cure this problem.. (Edited due to new procedure - see below)
 
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gordonmcmorran

Active Member
Jun 4, 2016
15
0
Hi VeeForce, I am having problems with my Ibiza 1.2 tsi but the actuator on mine is for the waste gate but thought you could possibly help , but mine is coming back with mechanical malfunction. I have vcds but just really an novice but willing to listen and learn, anyway when I put actuator into test mode using vcds I hear a high pitched sound coming from the actuator and I cannot move rod out or in , but I think this is normal .
Yet when I start the engine and run M/Blocks with the engine running at idle approx. 850 Rpm the charge pressure specified value is 452.40 hpa and the actual value is 994.18 hpa this looks too far out to me.
at idle again reading coming from actuator position sensor specified position 71.12% and actual position is 41.623% again this seems to far out could you please give me your thoughts or am I totally wrong here.
Thanks in advance.
 

VeeFource

Active Member
Dec 5, 2014
121
2
Hi,

If yours is a mechanical issue and is coming back with the P334b error code rather than the P334a then as I recall reading elsewhere it's because the vanes are sticking/gummed up. Have you tried undoing the linkage and seeing how freely the vanes move? If should be really easy to move the control lever with a positive stop at either end of the range.
 

gordonmcmorran

Active Member
Jun 4, 2016
15
0
Hi Veeforce thanks for getting back to me. On the 1.2 Tsi the turbo is not vnt it has a waste gate the actuator operates the waste gate, I have had the actuator off and the waste gate move freely, its as if the actuator needs calibrated, anybody any ideas.
 

VeeFource

Active Member
Dec 5, 2014
121
2
Oh yeah, I forgot! It's been a while since I've even though about it as the car's been fine since doing the mod.

What about doing the above and seeing how it effects your readings? Worst case is you can always file the end of the sensor boss to it's original length?
 

Scratchman

Active Member
Nov 9, 2016
33
1
Our 2011 1.2 TSi started giving these symptoms just over a week ago. As we bought the car used, I contacted Seat to try and establish if the shim and engine management update had been applied. In spite of 2 further messages leaving multiple contact details I've heard nothing.

We get the EPC light and "Start Stop Error" message at pretty much every start up, My OBD II reader shows just the P334A error. If I switch the start/stop off, the EPC error will clear only to return on the next start up when the start / stop defaults back to being on. Ambient temperature doesn't seem to be a factor. I've tried moving the actuator rod and it seems to move very freely.

Until I know if the 2012 update / mod have been applied, I'm reluctant to start messing about, especially as the nearest Seat dealer is an 80 mile round trip away.

I must admit to being pretty disappointed that such critical major components should fail on a car that's less than 6 years old and barely done 50k. As the water pump has also started leaking, I'm really staring to be seriously unimpressed with the quality of VAG engine ancillaries. Even less impressed with the wall of silence from Seat Customer Service.
 
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camelspyyder

2 SEAT-er
Jun 26, 2014
1,253
150
Our local SEAT dealer put a new turbo on our 2014 1.2 TSi when they couldn't permanently clear this fault, so the earlier recalls and changes clearly haven't worked 100%. Luckily the guarantee had 5 months remaining.
 
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VeeFource

Active Member
Dec 5, 2014
121
2
FIX FOR P334A ISSUE…

Having had a couple of 1.2 TSI cars that have demonstrated this fault and investigated further, it seems there’s a design flaw with the turbo actuators on this engine (located just to the right of the exhaust heatshield and mounted on the turbo). The internal position sensor’s plastic slides wear out and this extra slop allows the moving part of the sensor to become jammed at a self-locking angle to the fixed housing. To remedy this:

1. Purchase a 5 lobe security star drive set from Screwfix for about £20 to enable you to undo the 3 anti-tamper screws on the actuator. You'll also need some plastic grease (brake calliper grease will be fine) and spray on lube (must be high temperature & plastic compatible such as silicone or PTFE based - metal lubes may kill the plastics!!).

2. Undo the electrical connector on the actuator by pushing down on the jack whilst gently lifting the tab on the right (fingernails work best if you have them long enough but be careful as these connectors are notorious for becoming brittle and snapping. If this happens you’ll need a small zip tie to hold the connector together when you’re finished). When you see the clip release you can then lift off the jack.

3. Undo the 3 anti-tamper screws (receiving holes circled in picture in picture - two at the top and one slightly hidden at the bottom towards the front of the car) being careful not to drop them.

Actuator 1.jpg

4. Separate the two main halves of the actuator by sliding the black plastic housing to the right. It has runners to keep everything aligned so you'll need to slide it a good distance before it's fully separated but there should be room in the engine bay to do so.

5. Using a small flathead screwdriver, lift the retaining tab up from the top of the position sensor (circled in image) and the moving part of the sensor should now spring away from the housing but still be retained by the spring.

Actuator 2.jpg

6. Use your plastic compatible grease to lubricate the slides on either side of both the moving parts and housing of the sensor being very careful not to stress & deform the spring. Also grease the boss the spring sits on and then re-clip the moving part back into the housing.

7. Use your plastic compatible grease to lubricate the teeth on all the gears on the other half of the actuator (i.e. the sub-assembly remaining mounted on the car). Ask a friend to hold a small mirror and a torch and spray your plastic compatible lube around the metal slide and spring parts to the left of the gears as you won’t be able to get grease on there with it still being mounted in the car due to access.

8. Ensure the motor connector o-rings are clean and use your plastic compatible grease to lube them.

9. For good measure you can use some battery terminal grease on the motor connector prongs to ensure good conductivity.

10. Reassemble the actuator and reconnect the electrical jack.

11. Turn you ignition on full (no need to start engine) and check whether the actuator is making a high pitched tone. If it is, disconnect and reconnect the jack a few times until this stops to reset the motor.

12. Clear your fault codes as the car should now be fixed.

13. Enjoy not having to pay for a new turbo to be fitted which is the default procedure for this fault at a main dealer.

It should be noted this error is different to the closely related P334B error code which reflects a mechanical problem with the turbo bypass valve becoming obstructed.
 

csh

Active Member
May 5, 2018
6
0
United Kingdom
Hi @VeeFource thanks for the advice on this issue.

I've got the exact same error code combination on my 2015 Ibiza 1.2TSI at the moment and am attempting to fix it.

What kind of plastic compatible grease would you recommend using?
 

VeeFource

Active Member
Dec 5, 2014
121
2
Hi @VeeFource thanks for the advice on this issue.

I've got the exact same error code combination on my 2015 Ibiza 1.2TSI at the moment and am attempting to fix it.

What kind of plastic compatible grease would you recommend using?
Hi,

A silicone grease would be best such as this: https://www.amazon.co.uk/Silverhook...eywords=silicone+grease&qid=1604181114&sr=8-3

Or red caliper grease would also work if you have any spare.

Good luck with the fix and let us know how you get on.
 

csh

Active Member
May 5, 2018
6
0
United Kingdom
Good luck with the fix and let us know how you get on.
Hi VeeFource, thanks for the advice on your previous post.

I've had the module open this morning to check, and sure enough, the spring-loaded part was getting caught slightly at an angle.

I've applied the silicone grease as recommended and haven't had the issue so far today.
Of course I'm not using my car much lately due to lockdowns and working from home - however we'll see how it holds up over the next few weeks/months!
 

VeeFource

Active Member
Dec 5, 2014
121
2
Hi VeeFource, thanks for the advice on your previous post.

I've had the module open this morning to check, and sure enough, the spring-loaded part was getting caught slightly at an angle.

I've applied the silicone grease as recommended and haven't had the issue so far today.
Of course I'm not using my car much lately due to lockdowns and working from home - however we'll see how it holds up over the next few weeks/months!
Glad to hear that. Hopefully it's sorted now :)
 
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