[carguy138]

Had the weirdest thing happen today and not sure what to make of it. I'm the second owner of this car and got it in 2014 with around 20k miles. I change the oil every 5,000 miles and am OCD about maintenance. Car has been dead nuts reliable and currently has 70k miles. 2011 335i N55 and 6MT.

Quick summary: wouldn't idle and kept stalling the day after an oil change. Unplugging and replugging the MAF "fixed?" it.

Yesterday I changed the oil after 4,900 miles with Liqui Moly 5W-30 Special Tec and a new Mann 816x filter. Filled with 7 quarts, let it idle for 20 minutes and drove around for about a half hour. Everything seemed perfectly normal. Same oil and filters that I've been using for years.

This afternoon I started it up and it stalled about 30 seconds later. It has never done this before so I restarted and it progessively got worse. The only way I could keep it running was with a bit of throttle and keeping the RPMs above 1500. Scanned for codes and got the following.

Active Codes
2BEA: Mixture control: Fuel-air mixture too lean, large deviation
2E4C: Exhaust gas flap, activation: line disconnection (IGNORE THIS)
3427: Engine oil pressure sensor, electrical: Short circuit to earth.
3429: Engine oil pressure sensor, plausibility: Pressure too high before engine start.
342A: Engine oil pressure sensor, plausibility: Pressure too low before engine start.

DME Shadow Codes
2C42: Mixture Control: Multiple Fault

After reading this, I cleared the engine faults, restarted and the same thing kept happening. I logged oil pressure and was getting a constant 40 PSI at 1,500 RPMs.

Then I shut the car off, unplugged the MAF and restarted it. Idled perfectly and no rough running.

Then I shut the car off, replugged in the MAF and restarted it. Idled perfectly and zero issues!

I drove the car for about 30 miles of back roads, including a few pulls in 2nd and 3rd, and the car is running great. Codes haven't come back. The only thing I can think of is last week I dumped in a bottle of Techron before topping off with Exxon 93 but that's it?

Any ideas what is going on here? I didn't touch the MAF and can't believe it would make that much of a difference.

SOLVED IT! Replaced the oil pressure sensor, MAF (first sensor after air filter) and cleaned the connections on the TMAP sensor. There was some green oxidation on the pins on the connector.

Cleared codes and took it for a drive. Super smooth idle and runs great.

[Pladi]

Originally Posted by carguy138

Had the weirdest thing happen today and not sure what to make of it. I'm the second owner of this car and got it in 2014 with around 20k miles. I change the oil every 5,000 miles and am OCD about maintenance. Car has been dead nuts reliable and currently has 70k miles. 2011 335i N55 and 6MT.

Quick summary: wouldn't idle and kept stalling the day after an oil change. Unplugging and replugging the MAF "fixed?" it.

Yesterday I changed the oil after 4,900 miles with Liqui Moly 5W-30 Special Tec and a new Mann 816x filter. Filled with 7 quarts, let it idle for 20 minutes and drove around for about a half hour. Everything seemed perfectly normal. Same oil and filters that I've been using for years.

This afternoon I started it up and it stalled about 30 seconds later. It has never done this before so I restarted and it progessively got worse. The only way I could keep it running was with a bit of throttle and keeping the RPMs above 1500. Scanned for codes and got the following.

Active Codes
2BEA: Mixture control: Fuel-air mixture too lean, large deviation
2E4C: Exhaust gas flap, activation: line disconnection (IGNORE THIS)
3427: Engine oil pressure sensor, electrical: Short circuit to earth.
3429: Engine oil pressure sensor, plausibility: Pressure too high before engine start.
342A: Engine oil pressure sensor, plausibility: Pressure too low before engine start.

DME Shadow Codes
2C42: Mixture Control: Multiple Fault

After reading this, I cleared the engine faults, restarted and the same thing kept happening. I logged oil pressure and was getting a constant 40 PSI at 1,500 RPMs.

Then I shut the car off, unplugged the MAF and restarted it. Idled perfectly and no rough running.

Then I shut the car off, replugged in the MAF and restarted it. Idled perfectly and zero issues!

I drove the car for about 30 miles of back roads, including a few pulls in 2nd and 3rd, and the car is running great. Codes haven't come back. The only thing I can think of is last week I dumped in a bottle of Techron before topping off with Exxon 93 but that's it?

Any ideas what is going on here? I didn't touch the MAF and can't believe it would make that much of a difference.

If this happened to me i would be zeroing in on the oil pressure sensor. At least unplug it and plug it back in make sure no oil got in the connector or something

Alot of ECUs are designed to shut the car off when in idle when there is an issue with oil pressure sensor feedback or oil pressure. This is true for alot of modern cars and motorcycles.

The car wont shut off when driving or under load when the issue is detected. But it will as soon as wheel are not moving and idling.

So i personally think u have a bad oil pressure sensor or connection.

The short faults are never wrong. Not to ignore.

[carguy138]

Originally Posted by Pladi

If this happened to me i would be zeroing in on the oil pressure sensor. At least unplug it and plug it back in make sure no oil got in the connector or something

Alot of ECUs are designed to shut the car off when in idle when there is an issue with oil pressure sensor feedback or oil pressure. This is true for alot of modern cars and motorcycles.

The car wont shut off when driving or under load when the issue is detected. But it will as soon as wheel are not moving and idling.

So i personally think u have a bad oil pressure sensor or connection.

The short faults are never wrong. Not to ignore.

That's super helpful, thanks man.

The oddest part is that I haven't flashed the ECU, havn't touched adaptations or really anything other than the oil change in months.

[Pladi]

Originally Posted by carguy138

That's super helpful, thanks man.

The oddest part is that I haven't flashed the ECU, havn't touched adaptations or really anything other than the oil change in months.

Yeah ideally u have to work with whatever factual data you have. Which in this case is the codes telling us the oil pressure sensor signal ould have been an issue for whatever reason.

Anything else can be a coincidence and a rabit hole.

We tend to focus on thr fact that " I just did the oil change" that might be a clue... It might. Might not.

The codes are telling u part of the 'real' story. Go after the codes. Anything else usually a rabit hole.

Parts sometimes just break. Regardless of what u tuned or didnt tune..

Just my opinion on troubleshooting

[carguy138]

For anyone else trying to figure this out in the future...

I replaced the oil pressure sensor (on the oil filter housing), MAF (first sensor after air filter) and cleaned the connections on the TMAP sensor (on the charge pipe). There was some green oxidation on the pins on the connector.

Cleared codes and took it for a drive. Super smooth idle and runs great.