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2006 2.5 gas issues

1353 Views 130 Replies 2 Participants Last post by  billymade
i got this 2006 2.5 car today to help a guy out in fixing it. first he is complaning of it stalling at stops and that is started maybe a few months ago. then we got the p2082 code that seems to point to the t-stat. or at least some research talks of that being the first aproach to that code repair. he seems to insist it is overheating and the t-stat is sticking closed. now i ahve change out lots of t-stats and i have never had one stick closed so it they do it will be a first for me.

so these are the codes i got today the p2181 i clearedout for him a month or so ago just to see if it did return. i used a HF scanner and all i got was that code but then i put my oxwell nt616 scanner on it and got a few more codes

this is what i got today so maybe af ew guys can point me in the correct direction being this is the first vw water cooled i have working on

ok i got the car and on the lift and they had a oil leak that looked like the oil filter cup but after i took the cup off and the o-ring out it had a small divot on the fitler side of the o-ring but i'm leaning on the power steering hose causing that leak as the oil was way up inside the cover that was on that hose. and behind the filter on the block was real clean like something may have been splashing on that part of the block compared to the rest of the block.

so this is the codes in this order
p2181 current cooling system performance
p0171 current system to lean b1
p2181 pending
p0171 pending system to lean b1
p2271 pending 02 sensor signal bias/stuck b1 s2
p0300 pending
p0301-302-304 misfires. all pending i thing that is from the stalling issue he is starting to have
so for the p2181 i'm changing the t-stat out
for the p0171 i'm changing the b1 s1 02 outs.
for the p2271 he wants to change that 02 out but outside to keeping the engine light on i do not see that causing any issues for stalling at stops that may be form the TB or the IAC being dirty otr the IAC being defective.

so the b1s2 bias issue sound like a bad sensor the b1 also sounds like a bad sensor. the stalling to me sounds like the TB is dirty and or the IAC is bad or dirty. he thinks it is the t-stat causing the stalling issues now on a Youtube i found that one guy changed out the map the pvc the filter and cleaned the TB and then wound up changing out the cam sensor he said he did not get a code for the cam sensor so might i test for that also? i did not get a code for just what i posted.

so any ideas on the sensor and if that cam sensor may be the real issues for stalling and engine shut off and rough idling at stops? thanks for any ideas on this to get him back on the road
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On the coolant temp code, things typically narrow down to the temp sensor or thermostat; check the ross tech definition, freeze frame data can indicate the sensor or thermostat. Neither part is too expensive; so, you could do both if freeze frame info, is not available in your scan tool.

If in fact the engine is overheating, you might pressure test the system, confirm what the cooling temps are, the cooling fans are kicking on and look for possible water pump bearing is bad, causing the seal to leak coolant.

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The lean and rich codes; can be affected by a number of issues. If you have a scan tool, what can read live data; check fuel trims, for the current readings (+ or - 10 % is considered in the normal range).

I would start with fixing the cooling system issues; a cool system problem, from a thermostat or a incorrect temp sensor reading, can cause a rich condition.

Needless to day, a overheating problem; can cause a warped head, head gasket failure, etc.

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A common 2.5L issue for a lean code, dying problem; is the pvc diaphragm, which typically fails, causing a vacuum leak.

The diaphragm can be replaced; rather, then the whole valve cover.

We have seen vacuum leaks from a plug in the head, bad maf sensors and weak fuel pumps.

So, there are a number of things to check and test. You may have multiple issues going on, causing all these trouble codes, lean fuel trim , stalling, misfires, etc., and a process of elimination, should help you narrow down the problem(s).

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ok thanks tons for all that info.. i have to change out the t-stat only because the temp rose rather slow this past winter and then when he took off the filler cap he told me it had some pressure in the reservoir as it hisses when he lessened the cap when i did live data with my harbor freight scanner last fall i got the -2181 code and again some YT videos pointed to the t-stat. that scanner did not show the 02 sensors issues. so i got those codes this time when i put the foxwell scanner on it, i'm learning that scanner. so what we are going to do if just change these 02 sensors out because the engine has 126,000 mile and them may just need it anyway and then go from there.

they also found a bad oil leak coming from the front of the engine it looked like it was the oil filter o-ring but then when i got the filter out of the way i saw the engine block was clean behind that filter housing/adapter so i'm leaning on that adapter being bad, i did see some youtubes talking on that adapter. being a problematic oil leaking spot. and i found one adapter on amazon for 50$ so as long as i'm in there i will change that out as well.

i will double check all the air points to the TB and onward to the intake just in case it has bad seal the intake broken or o-rings on the intake to the head and i will take the pvc off and inspect the diaphragm and maybe i can get the diaphragm if it is defective.

also you sent a link for the p2082 exhaust gas temp but that may be related to the p2271 what is funny is b1s1 is telling me i have a lean condition and b1s2 is telling me i have a rich condition. i do not think i can have both so i will work on the lean condition for a bad pvc or cracked o-ring or tube at and after the TB or even bad or missing o-rings on the intake to head. when i started taking off the intake i found the injectore did not have the locking clips on them so that tells me someone has been in there and may have missed something. also i will clean the TB and check the IAC to see if it actuates when i put power o nit and make sure that port is as clean as i can get it. if this sounds like a plan let em know if i missed something let me know.
thanks much for this help
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If you end up replacing the 02 sensors; stick with the oem quality from Bosch.

If someone has been “in there” with parts missing; i would double check everything.

View live data and the furl trims, after each new part or repair, this can help you confirm fixes.

A common oil leak issue with the 2.5L; is the vacuum pump, a gasket/seal kit, is the fix for that. Members, have installed the RKXTECH kit with good results.

billy i took off the pvc and it had a tear in the diaphragm so that must be the 1005 lean on the b1s1 and most likely the b1s2 bias so we will hold of on them as they are easy to change out later if needed. also look at the pvc and see how dirty it is at the port that is going to the T/B so i bet the T/B is dirtier than it appears looking into it now with the mirror

so tell me on the oil leak i found 2 o-rings ,one was on the oil filter cap that the oil filter actually sets in and i found one up in the adapter i had to dig that one out with a pick tool. so in my 40 years in machine repair i have never had a double o-ring setup. but looking on rock auto for the oil filter for this engine i do see 2 o-rings. so does this engine take 2 o-rings or did the oil change guy forget to take the one out that was on the oil filter adapter and then put a 2nd one on the cap and that might be the oil leak issue?

i looked real close and there is no clean area above where the cap and the adapter are assembled. i'm leaning on the double o-ring being that issue. also when i took the oil filter cap off it was on there so tight i almost had to put a cheater bar on the oil filter wrench so i wonder if the oil change place while testing the engine for leaks saw that leak and just torqued the **** out of it to slow the leak down?? photos of what i'm seeing

diaphragm, oil spot where it is clean, o-ring still on the adapter, oil ring that was on the cap, both together,
let me know what you guys think? i do not think i need to put on that adapter, unless just because i'm already in there and for 50$ just do it ? also the power steering hose was full of oil under the cover. i do not see a color change so it may be the oil filter was leaking to get oil up in that as well, however as fr up that line i found oil under that cover it almost makes me think that line may be leaking also. but that can be another day. also i told him not to get the 02 sensor just yet to seeif those codes go away after the pvc is repaired.



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ok i have to find that part i'm having a time finding all these, this is my first vw water cool engine ever, i have done air cooled tons of times. he did that already as he did have that leak and fixed it so now on to the next one. but now i think i is going to get the t-stat and the oil filter adapter being amazon has it for 50$ and i'm in that area. the pvc valve, we are not doing the 02 sensor yet as they are easy and because i found that pvc bad that tells me the engine was real lean and that was the root cause for the p0300 codes and the sensor coeds. so i will start with the most obvious and work from there. did you see the photos? that may tell you the story and help with suggestions. thanks
The pcv diaphragm is definitely bad; many prefer the RKXTech pcv repair kit, over the Dorman version.

Well, the oil leaks are common on the oil filter cover; i would replace all the o-rings and check the plastic cover for cracks, there are metal upgraded versions, if it needs replaced.

I believe there is only one large o-ring for the housing; review this video for more info:

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thanks it looks like the oil place did not take out an old o-ring this video show only on oil ring for a seal. however my oil filter cap does not have that center pc that the filter fits over so i wonder if i need a new cap? if so i might as well redo the completer unit and take away the other oil leak possibility later down the road if it is not now leaking. being i have this apart this far? also in the video he did not use much effort to remove the housing and i had to so that tells me it had a leak from the last oil change they do not just get tighter, they may stick a bit but like i said i had to put my back into that one. i almost wanted to go and get the mfg socket for ti .


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ok the t-stat opened around the 200 deg mar with a heat gun and temp scanner pointing at the temp unit on the t-stat it say o6 on ot so it must be original. it could be intermittent i guess. i see the TB does not have the IAC on it is is controlled by the ecu it has a small gap it ifor idle speed starting and my guess is the ecu will control the amount it is held open. i have not inspected the manifold o-rings yet but i did not see any signs of dirt around the ports so that is telling me the were sealing fine but the ports are a bit dirtier than i was expecting. kind of oily looking. there is not much oil around the top of the engine some over by the oil fill poet and that may be the bit i see at the sensor that is next to the oil fill port it looks like the oil cooler adapter has 3 bolts holding it to the block and it is not excessively oily, kind of normal for a 17 year old engine.

so if the owner chooses to change out that oil cooler adapter while i have it opened to the area i will just change it out. let's hope the amazon parts are ok he can't afford 300$ for oem. plus it concerns me the center is missing from the oil filter cover but i see on rock auto the filters there look like the one i bookout i did not see any cracks in the oil filter cover so i'm leaning on the 2 o-rings were the issue. it is going to be fun gettin gthat bottom center screw back in the intake. i see they have keepers to hold them but half the screws came all the way out and that center one fell down and got caught in the engine by the alt area.
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I would replace the thermostat; oem for vw is Mahle/Behr.

FCPEuro.com is a good VW parts supplier; if you have to special order things.

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i don't know where he going for parts. because he need the car my guess is he will not want to wait long for them. but i wll go to that site now and see prices and avaliby on the t-stat and the oil filter adapter assy. thanks
ok i got the adapter off and i found it did not have 2 o-rings on top of each other it seems to have one down inside and another one on the top. but i tried to put the canister on the adapter without o-rings and it would not go all the up to the flange on the canister to the adapter. i had a hard time getting it even close. so it seems the plastic has just been heated so many times that is seems to have started to get misaligned. also the o-rings on the back side were getting brittle i could not poke them with a small screwdriver for testing how soft they were. so he is getting a new unit the adapter and canister as a complete unit. because it was leaking oil i can't see any breaks in the canister but after i tried to put them back together on the bench to try and see why it was having issues it may just have a crack in it that when under pressure and heat opens up and sprays oil out. so i will be changing out the pcv unit the t-stat and the oil filter unit and put it back together and see how it goes from there. thanks for the help and i will let you know how all this works out in a few days.
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Because the assembly is plastic and are removed so often, it is a common leaking problem (thus the aftermarket metal upgraded versions are sold).

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thanks i will bring that up to him but because of how old it is he just may not go for that metal unit unless he can source one off ebay. i would guess this one is going to last about as long as they will have the car at this point. but i will tell him. parts are not in the mail and tomorrow i should be reassembling it and will see how it runs i'm leaning on the sensore being ok and that the huge tear in the pcv diaphragm caused so much of a vacuum leak that caused the lean on the b1 sensor and that caused the ecu to send tons of gas into the cylinders and then not burn and that caused b2 to run rich. anyway after i get it running if the engine light returns i will see if it is the sensors, if so they are easy to change out. i will keep you posted. thanks
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