[Robmwert]

Hello,

I've been reading a lot about N53 and it's issues as I am currently having one.
Symptoms :

• Car goes into limp mode - previously no issues at all and no symptoms. Was just about reach my destination - orange check engine light came on with message "Full engine power no longer available...." Oh.. great. I parked and after 3 hours, came back to drive home. 80 km ahead of me and not a single issue on the drive.
• Following day morning cold start - car starts shaking as if the engine wanted to jump out of the car. Driving it very moderately and carefully because I need to go to work - if I tried to accelerate a bit more, the car started shaking again, if revs dropped low - same shaking. Had to pull over to get gas. After I fire up the engine again, smooth as ever.

On that same day, I decided to go to independent BMW service regardless. Had the diagnostic tool read the codes, many various codes with couple cylinder misfires. The mechanic performed various kinds of testing via the diagnostic tool.
First HPFP - seems to be ok
Next injectors - he commented the deviation values seem to be of a new injector. I am not really educated on this but I was watching the monitor as the car was idling (engine was of course warm) and it was shooting between around +60 to -60 across all 6. It was ruled out.
NOx sensor next - it was determined to be absolutely dead. Scheduled a replacement next Tuesday.

After reading all the discussions on different platforms, I can't help but feel that new NOx isn't going to help this. I'd like to think that as a feedback loop component, it just doesn't do it's job to regulate and could potentially cause a misfire? You can educate me on this. The mechanic however did not do any manual inspection of the other things like injectors or pump.

I was also thinking that perhaps ignition coils could be going bad. I had spark plugs replaced just couple weeks ago but not the coils. So what to expect? Is it going to be the dreaded injector problem? To be honest, I've accepted the fact that in time, it will have to be replaced regardless and I absolutely love the car so it isn't much of an issue. Just trying to make sense of things.

Also, today after the mechanic deleted all the codes yesterday, cold start was smooth but after 10 minutes of driving, again the car went into limp mode. Parked, waited for my girl to come back from doctor and after I started the car again, was smooth again. So same thing on repeat. I am not driving this car until Tuesday when I have to go for the NOx change. Expecting a rough idle though.

[ctuna]

If something goes bad after service it's reasonable (or installing new parts)
to think something went wrong at the service.
Did you replace the plugs yourself?

How many miles on the car?
Coils ever changed?

[Robmwert]

Originally Posted by ctuna

If something goes bad after service it's reasonable (or installing new parts)
to think something went wrong at the service.
Did you replace the plugs yourself?

How many miles on the car?
Coils ever changed?

It has only 77k km (around 48k miles). The car was serviced at a reputable place.
The plugs were replaced there. We knew already previously, that the NOx is reaching EoL. Now it is confirmed dead.

I also suggested the coils to be replaced as well just to be sure but did not yet receive a response (messaged them late yesterday) but we will see how things go. Also another detail - the car doesn't hesitate on start. It is more or less instant which also makes me think that the pump is working fine.

Also I am the 2nd owner and I realized, that the cars with this motors had recall opportunities unless it's been claimed by the original owner which I dont know. Contacted authorized dealership to make a check for my VIN but of course again, it was late Friday so I will know more on Monday.

[sonofsun]

Without the codes it's hard to guess what could be the problem. I had limp mode issues when my crank shaft position sensor went kaput. Could be Vanos solenoid issues or camshaft position sensors, injectors, coils, all kinds of stuff.

I also had a limp mode error when my coils went bad. Lucky for me I always have my Foxwell NT510 in my glove compartment. Immediately scanned the code, went home, swapped the coils and saw the error change to a different cylinder and ordered replacement under warranty from FCP Euro.

[Robmwert]

Hello I have an update.

It is in different languages so I'll just post the actual codes - these are from around the time of my original post.

After my initial visit to the mechanic, he deleted the codes and one morning I had to drive my gf to a doctor. Went into limp after like 15 km drive while it was already warmed up. After engine restart it was driving normally and no more issues from that point. Also the rough cold start hasn't happened again.

I had NOx replaced yesterday for Vitesco (basically the BMW original) and all coils replaced as well. He also checked the codes from my last drive (where it went into limp as I described above) and there were 2 codes that caught his attention but he couldn't make sense of it. Rich mixture and low pressure which according to him really don't make sense. Also there were no cylinder misfires logged.

Drove already like 100 km after the replacements, pushing it a little on highway, hard acceleration from stand still and it is driving great so far. I will post again if anything goes wrong again but so far I am happy.