Help with code 28A0 on N55
 

Im getting the code 28A0 “intake pipe absolute pressure, plausibility: pressure too high” and looking for some troubleshooting help. I’m also getting a 2820 shadow code, “absolute pressure sensor, intake pipe”. I’ve already taken off my chargepipe, throttle body, and MAP sensor to clean. Don’t see any cracks or anything obvious and still having no luck. Truck starts fine but idles rough. Code points to possible MAP or throttle body malfunction....anybody experience this before? Also found something about the evap purge valve could be faulty, but don’t know if it would throw this code specifically. I have a friend coming with Rheingold to reset some adaptations to see if that helps anything. Any help in the meantime would be appreciated.

Id replace the MAP sensor. Its only $100 or so.

Yea I’m likely to start there. I’m also reading into the N55 PCV valve issues along with the main seals. I’m getting a clattering, ticking sound upon starting other than the normal injectors and lifters. There is also a gap between my front crank seal and the end crank plate. Wondering if that’s causing vacuum issues as well which is giving a code for too much pressure.

hey i have the same codes on my n55 335i, i also have a n55 x5 with no codes. i swapped the map sensor on the charge pipe, but the code didn't go away. did you figure it out yet?

Well yeah to a degree I think I know what’s going on. My serpentine belt shredded as I was pulling into my house when this all began. Luckily wasnt going fast at all but it seems to had been enough to break through the crankshaft seal. It’s currently at a friends shop now for oil pan removal to get any pieces out. The truck started fine but after a few seconds it would get the oil ticking noise. Couple people told me it sounds like oil starvation as well which correlated that some of the belt is probably clogging the oil pump pick up tube. Makes sense so I had it towed to the shop without starting it anymore to limit further damage.

Before coming to this likely conclusion, my buddy came with rheingold and it offered various things to check. Sensors were obvious ones, checking the throttle body was another. I had already done that. But my leak and variation in pressure is likely from the crank seal. A clogged PCV valve was also something it mentioned you could look into, but that unfortunately requires changing the whole valve cover as it’s built in there on the N55. In extreme cases, I came across people that had bearing caps failing on their camshaft, but that guy was over 100k and mentioned lack of oil changes. I mean I bought my X5 used and only has 57k on it now, can’t imagine it would be that extreme especially since I got the code right after my belt snapped.

How exactly did yours start? What symptoms were you having? Any other codes being thrown?

If you wanna be paranoid....

2012 35I Code 28A0 throttle angle/intake pressure - Bimmerfest - BMW Forums

:(

Yeah that’s the link I was referring too. This has got to be a super extreme case which involved poor maintenance. I’ve read also that all some people had to do was reset their throttle adaptations and that same exact code never appeared again. Guess it’s just a wide spectrum of what it could be exactly.

Hey thanks for the info. Ha same issue. I thought I had fixed the ofhg, a few weeks later the belt shredded. I did a scope inside the timing chain to crank, no belt inside. Drained oil a few times and just a few tiny belt bits came out initially, but all clear now in the filter and drained oil.

Car has good oil pressure at all rpms, sounds good and drives good so far.

Damn I hate this car....

I try swapping the maf and map on the intake manifold, if that doesn't work, I'll just trade it in I guess

As the model ages, and people trade in time bombs- it might not be shocking if new BF owners wind up buying these disasters....

Update so far, I've swapped maf and intake pipe map, no luck. Next I'll swap the map sensor on intake manifold.

changed the map sensor on intake manifold, no change. codes still back on. time to go trade in this motha

That sucks man. I’d recommend checking your front crank seal. Just need to take off the fan, belt, and crank pulley to inspect. It’s not that bad.

My code is now gone. Belt got past the seal and into the oil pan. Ended up costing me $1500 to have a friends shop drop the differential and subframe to open up the oil pan. Shreds of belt we’re all in there. I was lucky nothing ended up in the timing chain. Also had him just change my water pump as preventative maintenance while everything was exposed there. At 57k, I’m sure I was on borrowed time.

Now I’ve encountered another issue as a cause of the belt. It appears to have wrapped around the pulley and severed the ground wire for the AC compressor and it’s beyond repair. Now it’s back at the shop for an AC compressor. Can’t go without AC in this Vegas heat, especially with 2 young kids. Hoping after this all is well. Other than them telling me the VCG has a very minor leak which I’ll take care of later. Nothing major at this point but better to just replace the whole valve cover on these things. Learned my lesson with my E90 in that regard.

Hey man, glad the code is gone on your car. So when the belt shredded, I took out the crank pulley and removed all the belt that was wrapped around. I did 3 oil flushes on the car, tiny belt pieces came out on the first drain and in the filter, on third drain, didn't see anything in filter and oil. I did a scope thru timing chain and didn't see any belt in the chain or on the crank shaft inside.

The crank seal looked ok when I saw it but maybe it's not fully sealing. Maybe it did rip.

I don't really feel like dropping the subframe so I'm gonna see if the cel doesn't come on then go trade it in. Just tired of having a daily driver that is a weekend project. Had way too many things give out under 100k.

Thanks man

Update on 28a0. I changed my crank seal. The original looked ok, but when it took it out after tons of pain staking tries then finally hiring a mobile mechanic to use brute Force, the inside seam seems hard and plasticy. So maybe it was almost on its way out at 85k.

Code has gone away now after new seal. Seems all go so far as to driving 20 miles. 0 codes. Thanks alot for your guidance. Hope this helps others

Race rpm, Have you had any issues since you change your crankcase seal???
Had the same issue, but I hope I caught it early enough...:thumbdown:nervous:

Hey, I drove the car for a few hundred miles then traded it in. No issies. I haven't used my tools in the garage since. Feels good to reclaim my weekends lol.

Hey Racermp, any chance you have logs from before the code showed up, logs while you had the code, then logs after you got it fixed?

I'm curious to compare our logs.

I've been fighting this code since July...

i don't have logs, but i don't think logs would show the issue. my oil pressue was the same before and after. the issue was the engine could not get enough vacuum pressure due to a torn front crank seal. you may have the same issue, or maybe a different vacuum issue.

Did smoke test and no leaks and changed valve cover and gasket.
Tried new map sensors for both locations.
And code 28A0 kept coming back.
Even with smoke test it did not have a leak but my mechanic said the flap was staying open on the Fuel Tank Vent Valve.
Changed the Fuel Tank Vent Valve and the code went away.

Any theory on how the Fuel Tank vent valve was causing 28A0, “intake pipe absolute pressure, plausibility: pressure too high”??

My mechanic told me after smoke test no signs of leaks so I narrowed it down to all the breather outlets that have air and found the vent valve to have a small leak that was undetectable. Whatever the case just glad the code went away.

Very interesting. Depressing too. Sometimes these little leaks, cracks, broken hoses are a total PITA to find!