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hi bought a 2005 a4 2.0 tdi 140 every now and then goes into limp mode switch off engine restart everything fine took egr valve off today cleaned it , it was not that bad really maf looks new, car a had turbo about a year ago guessing who ever did it cleaned egr then, while in limp mode today got a code checked it was turbo underboost po 299 no engine light on dash and when car was restarted no fault code so trying to find what to check next can anyone help me thanks :1zhelp:
Check all visible pipes/hoses and have a look here
16683/P0299/000665 - Ross-Tech Wiki
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I had that exact same fault, and it was a cheap fix. It was the vacuum actuator on the inlet manifold. Inside there is a diaphram which splits. you have to replace the whole unit. Only about £10 + another £10 for new gasgets. You will also need a couple of cans of choke cleaner to clean the inlet manifold out while it's off. It's quite an easy job. The unit is used to operate the flaps inside the inlet manifold and when split does not function properly. however mine is a 2007 so it may not be the same on yours.
Car runs great afterwards
Here is a pic of the part, it is at the top of the engine near the front. Part number is S03G129061C
Attachment 21399
thanks will check all
Hi all, just move over from the A2 forum, have an Audi A3 2.0 TDI. 09 plate. It’s another P0299 code fault - Turbo issue. I had this happen with the glow plug warning light coming on for a couple of weeks and then the engine management light come on with it last week. Usual loss of power. But after switching off the ignitions= it reset its self ( Glow Plug only) I cleared the fault code. And set about problem solving it. I change the oil,filter, fuel and air filters. “Been naughty and failed to do it last year so its gone nearly two years with 24k on the clock- I know, not good. So, having done that I tried the car over a few days and it had little effect on the P0299 fault. I then inspected the car and noticed the N75 sensor wasn’t on its mounting, just hanging down. Now the top Grey cap is sitting up right on its holding clip.( this wasn’t taken off when removing the oil filter but I had it serviced at a garage the year before- well near of 2 years and they left it hanging down.
Now, one day has passed and there is improvement – it failed go into fault over 50mph which it did previously. I then added some Forte Diesel Cleaner yesterday and since then I got the car up to 70mph with out a failure, but above that I had one glow plog warning come on. I stop the car turned off/ on and cleared the fault and drove on again reaching 80mph for about 10 miles and it came on again, I again stop and switch off/on and continued driving home and after 20 miles I ran it at 80mph and for the last 20 miles no return glow plug warning and loss of power.
Question: is it critical to have the N75 sensor vertical? Could this be the root cause?
Or has the magic Forte turbo cleaner worked?
Or possible a combination of all 3 with the filter changes?
(Ps also ensured all pipe work no leaks which there wasn’t)
Your views.
hi all just a update i checked all pipework etc all seemed good , i then checked air filter it was a bit black lol so drove with no air filter in when i went to buy a new one wow car was great lots of power and no limp mode , i put new filter in on sunday and its been fine since so maybe its ok now but will keep you all posted but for now im happy , im sure it cant be just down to a mucky air filter but hey its working so far .
well its done it again after 2 weeks thought i had fixed it but no im sick of it so heres my problem im looking for the vacuum actuator on the inlet manifold. as one guy said it could be that but i cant find one on this car i have 2 on the other side of engine above turbo but none anywhere near the egr unit
Just to add to my fault: I've change N75 solenoid and the Vacuum little pump and the MAS - still have the same issue. Did notice a leak on the exhaust manifold, soot and I took the clamp off but unable to force apart to look into the Turbo side but there is oily soot on the clamp*. I tighten it up and tested but still my fault is there. I can make it fault by driving in 6th gear at 70mph and at 2100 revs if I accelerate hard it then its a flat point and the glow plug warning comes on. If I stay in 5th gear and do the same its ok. So keeping it in a low gear is fine but to higher gear and over acceleration and it cant cope. I've pulled a vacuum on actuator and had some movement on it, but not sure if its fully functional. * I'm thinking the turbo is fouled up with oily slug. Was thinking of flushing it with tubo cleaner but ive got to the point now where I'm gona take the bullet and remove the turbo for cleaning but whilst i'm capable of that my heart isn't in wasting a day doing so getting black and bruised so may its of to the dealer and have them tell me its the Turbo !! Here my last scan : Address 01: Engine Labels: 03L-906-022-CBA.clb
1 Fault Found:
000665 - Boost Pressure Regulation
P0299 - 000 - Control Range Not Reached - Intermittent - MIL ON
Freeze Frame:
Fault Status: 10100000
Fault Priority: 2
Fault Frequency: 5
Mileage: 161037 km
Time Indication: 0
Date: 2013.07.25
Time: 12:57:08
Freeze Frame:
RPM: 2208 /min
Speed: 114.0 km/h
Load: 52.9 %
Absolute Pres.: 1703.4 mbar
Absolute Pres.: 1285.2 mbar
Lambda: 100.2 %
Lambda: 24.5 %
Attachment 21665 Here' a picture of my engine layout hope that helps. There is no 2nd actuator on the inlet manifold as you state but I guess its now a solenoid which controls the throttle type valve from the turbo unit pipe
control range not reached. it is underboost. it could be vacuum actuator leaking on turbo. not sure if audi do they but vw do a repair kit for turbo actuator for around £100 (can't remmeber exact price). bit tricky to replace. but can be done. just plug any vacuum pump to actuator and see if is leaking.
sorry for my poor english