[banane8]

I cant express how grateful I am for your time and help, as I wouldn't have a clue where to start or what to look for otherwise This community has added an extra dimension to my 124 ownership since I first came here to inquire about buying one.

 

[SteveP.]

My take on this (P2262 no longer present, P0299 now sets) is that there were, most likely, 2 separate issues. So you fixed one by replacing the boost valve with the OEM unit - or, conversely, you minimized a fault by replacing one boost valve that was faulty with another faulty boost valve (just that it wasn't as faulty as the first one). In any event, here are the possible causes of an active P0299 (from the service manual): A) Restricted Air Filters B) Boost system pressure hoses restricted or leaking C) Small intake system leak or restriction D) Exhaust system restriction E) Wastegate solenoid (faulty) F) Wastegate valve sticking G) Turbocharger faulty (turbine drag). Time to go back, inspect all system components and plumbing, look for any possible leaks and restrictions. Good Luck, Best, s

 

[alltimesaresoon]

for P0299 underboost, i can't advise the best. I have a stuffed turbo and it and the automatic really don't like lugging the engine. Lugging the engine is when you are in a higher gear, say 4th or 5th, but low revs, under 3k maybe and you give it a good bit of throttle. i'll get p0299 anytime i do that. Do you know if it happened when you were in auto or manual mode? ( i guess 1st i should ask if you have a manual or auto car)

My question now is, do I have an air leak at all or was the noise from the transmission after all... and is it just the wastegate solenoid that's shot? How do I know if the wastegate solenoid is functioning properly? - 1st part - boost leak check is how to confirm if you have air leak. WG solenoid proper function - i've swapped them to check, but they are about 175 bucks, so not maybe the best option. it's not hard to remove and clean out

P2262 - either way, as long as it doesn't come back, don't ask too many questions, just be happy. If it comes back of course, new information.

For the P0299, it's a common code, and it's a lesser limp mode, allowing about 6 psi (P2262 limits you to no boost, zero). With P0299, when it happens, i just turn the car off, start it. repeat a 2nd time. Turn on the yellow cruise ready light. Drive on.

Reason for the yellow cruise light is that it's connected. So when you get EITHER P0299, or the overboost code, or the P2262 code, this light will turn off and you will lose cruise control function. This indicates quickly that you are in limp mode and you don't have to then "sense" it from the loss of boost/power. It's the quickest diagnostic. don't need code reader for it. you do need code reader or program like obdfusion to monitor and see which code it is....

 

[alltimesaresoon]

also, update to MY P2262, since it may or may not help you diagnose.

Turns out it was NOT from the big boost leak at throttle body as i suspected.

It's in my tune from my tuner, and has to do with requested boost being too high compared to what is possible for the condition i was in (3341 rpm and 33% engine load, actual at 5.37 psi boost, vs ??? requested in the tune).

I've flashed back to stock to observe.

I DID have a bad connection at the throttle body, and a boost leak there, but it wasn't as big as i surmised and wasn't throwing the P2262

 

[banane8]

Do you know if it happened when you were in auto or manual mode?

I have an automatic and I suspect it happened when I was driving in semi manual mode in 3rd gear but could be 4th. There was no immediate warning lights, but I was coming to a stop at an intersection, put it back in auto and it was in limp mode.

With P0299, when it happens, i just turn the car off, start it. repeat a 2nd time.

Ok, so if I let the car sit - maybe unhook the battery for 5 minutes - and turn it on, should P0299 clear itself or do I have to clear it? And if there's an air leak or other issue at hand, presumably it will emerge again on a bit of revs?

 

[alltimesaresoon]

I have an automatic and I suspect it happened when I was driving in semi manual mode in 3rd gear but could be 4th. There was no immediate warning lights, but I was coming to a stop at an intersection, put it back in auto and it was in limp mode.

THAT HAS HAPPENED TO ME. DONT SWEAT THAT. JUST RESET

Ok, so if I let the car sit - maybe unhook the battery for 5 minutes - and turn it on, should P0299 clear itself or do I have to clear it? And if there's an air leak or other issue at hand, presumably it will emerge again on a bit of revs?

EASIER THAN THAT. PULL OVER. TURN CAR OFF WITH START STOP BUTTON. TURN BACK ON. ITS RESET. BUT TURN OFF AGAIN, RESTART. NOW YOU CAN SET THE YELLOW CRUISE ON LIGHT SO YOU CAN USE IT AS A REAL TIME INDICATOR

sorry for caps, used so i could put my replies in and differentiate from your part

 

[banane8]

Adding some more info just for the continuation and future readers coming here. Posting some pictures of the low boost pressure (according to Torque Pro with car profile as 1.4L / Petrol / etc.).

@alltimesaresoon It's definitely constant low boost but it's not triggering a CEL (stays as pending) and the cruise control trick is useful to know.

I hear the whine when it's under boost again. At this point I'll probably need a good mechanic to look at it.

Idle

Under rev up to peak 4k

 

[SteveP.]

Hi @banane8 , I'm thinking you have probable done a search in the searchbar for "P0299", but if not there are a good number of threads concerning this DTC as it is quite common. Two that I read had that have struck me as being maybe a bit difficult to diagnose was " P0299 CEL UGH! (Turbo underboost) " where @Mike34 had a diverter valve electrical connector not fully seated or a connector terminal issue. Another that struck me was the thread " P0299 Underboost problems " where @alltimesaresoon had a small split in the FMIC hose - split was down close to the steering rack. If you haven't, maybe review these threads and a few others. If you don't come up with anything after that, then I still think a pressure test with a smoke machine or just pressurized air and spray with soapy water. Good Luck, Best, s

 

[banane8]

I had no cruise control and I did @alltimesaresoon's on/off suggestion and I was able to activate the cruise control light (yellow) after that. The boost pressure graphs are with the cruise control light on, and show about an 8psi difference under boost. The pending P0299 remains (do I need to clear it?) and no CEL, so I'm not sure if I'm in a "lesser limp mode" or driving without limp mode and underboost.

Reviewing all threads and info I can find on the problem.

Will try with spraying soap and a compressor hope I can see something without raising the car.

 

[Mike34]

Hey I'm a Zombie thread famous! As a follow up...After I did the disconnection / reconnection and used the corrosion block, I never got that code again.

good luck brother!

aloha mike

 

[Onus]

Hello guys,

I am having the same problem. Won't shift from 3rd to 4th unless I hit red line. Sometimes it happens from 2nd to 3rd but not as much as 3rd to 4th. I noticed my check engine light came on about 50 miles after first running into this issue. The code came back as the p0299. I was changing the air filter when I heard a clunk sound from inside the hose that runs from the air filter to the turbo. It turned out to be a metal cylinder used inside the hose. It was sitting sideways in the hose when I found it. However, after reinserting it the only difference was my boost and power have come back but I'm not sure if I'm at a 100% yet. There's still that loud whine and gears won't change unless I hit redline in rpms. Manual shifting shifts no problem but still I feel a small leggy like engine and pull after each shift. The rpms drop and kind of lagg after the shift and I feel as though I'm not getting full power. After I fixed that hose obstruction I disconnected the battery and let sit for 2 minutes and so far no error codes. But I still can't switch from 3rd to 4th automatically without hitting high rpms. And what scares me most is the slow lag and drop in rpms after each up shift.

 

[banane8]

Sounds like you're still in limp mode. It'll comply with your command but auto will stay in low rpms and max 3rd afaik (unless you're killing the engine and it has to?) After clearing my limp mode, I shift up to 5th no problem in auto. It just takes forever to get there and is certainly not recommended, but shifts at normal ranges.

Are you able to turn on cruise control? See the previous couple messages about that.

 

[Onus]

Sounds like you're still in limp mode. It'll comply with your command but auto will stay in low rpms and max 3rd afaik (unless you're killing the engine and it has to?) After clearing my limp mode, I shift up to 5th no problem in auto. It just takes forever to get there and is certainly not recommended, but shifts at normal ranges.

Are you able to turn on cruise control? See the previous couple messages about that.

Update*

I am however able to use cruise control. Still creeping up on my appointment to take her in on the 23rd. It just can't come fast enough 😩

 

[alltimesaresoon]

I suspect part of my p2262 issues are an intake manifold small leak. I only trip when under very little load and pedal. I think air is getting in

 

[banane8]

I'm back.

Had another look at the car and I'm not aerospace engineer but even I know this don't work for air pressure

Turbo inlet hose

I didn't put ir back since it looked melted, wanted to ask for further advice here.

Should I...
1. Get a new ring?
2. Ignore it and put it back (turbulent air flow?)
3. Cut off the wobbly plastic to just the ring and reinsert it?

 

[alltimesaresoon]

What IS that? It's definitely blocking your airflow and that's your likely culprit.

 

[banane8]

The metal ring keeping the hose diameter from shrinking (is what I'm guessing is its purpose).

Saw a bunch of other guys with the same issue and P0299. Only their rings didn't seem to have the black wrapping and showed bare metal (it's metal underneath).

 

[banane8]

Here's the other case of this ring having twisted. Notice there's no wrapping on it. Just picked it up and across country we go.

 

[alltimesaresoon]

I'll bet you got rid of your code. Good job!

 

[banane8]

Thank you! Wouldn't have gotten anywhere without this forum, you extra helpful few and the motivation you gave me along the way. I'd say so unless I have more issues - will report back tomorrow.

I wonder if they removed the rubber wrapping due to it melting. Mine is a 2017, and his (with bare metal ring) is a 2018.