[OTO335i]

Hey guys,

Anybody know what this code is for? Started getting it Saturday night and the half engine light is on. Code went away and then i received a missfire on cylinder 3 yesterday, erased that and car ran fine for the rest of the evening.

Driving my car today and half engine light came on again with code P311B but no code referring to missfire on cylinder 3..

Any advice helps!

Thanks

[gbalthrop]

Originally Posted by OTO335i

...Started getting it [P311B I presume you mean? ] Saturday night and the half engine light is on. Code went away and then i received a missfire on cylinder 3 yesterday, erased that and car ran fine for the rest of the evening. Driving my car today and half engine light came on again with code P311B but no code referring to missfire on cylinder 3..

Here's the Definition for that Code from BMW Fault Code Lookup:
N54 | P311B | 2E32 | DME: Fuel injector, cylinder 3, activation | MSD80 | Engine electronics

Bentley's Definition for same Fault Code:
P311B | 2E32 | Cylinder 3 High Pressure Injector Low Side / High Side Electrical

I don't know WHAT exactly is sensed that causes that code to be set. There MAY be an intermittent open circuit in the Sensor Power & Ground Pulse, or whether the DME electronics (MOSFET) are NOT working properly to produce the Ground pulse for Injector #3, but SOMETHING is intermittently NOT functioning related to the circuit for Injector #3. Since "misfire" is measured by slight slowing of crankshaft speed on power stroke of one cylinder as compared to preceding & succeeding cylinders in firing order (as opposed to an electrical measurement related to coils or plugs), an injector fault can cause a "misfire" (P0303) on cylinder #3, just as an ignition fault can.

So the cause of your P0303 and P311B is the same: Injector circuit for Injector #3. Here is TIS circuit for your injectors, along with Installation Location:
https://www.newtis.info/tisv2/a/en/e...ection/dAB3Dk4
https://www.newtis.info/tisv2/a/en/e...xi-lim/S82VdKI

I would start by disconnecting the Connector, X6103 at the Injector (Y6103), checking for any corrosion or damage/ looseness in the pins & sockets, cleaning pins & sockets with Electronic Contact Cleaner, reassembling, clearing all codes, and seeing if, and under what conditions (Freeze Frame Data) any code recurs. ANY P-code reader can read those codes.

George

[OTO335i]

Originally Posted by gbalthrop

Here's the Definition for that Code from BMW Fault Code Lookup:
N54 | P311B | 2E32 | DME: Fuel injector, cylinder 3, activation | MSD80 | Engine electronics

Bentley's Definition for same Fault Code:
P311B | 2E32 | Cylinder 3 High Pressure Injector Low Side / High Side Electrical

I don't know WHAT exactly is sensed that causes that code to be set. There MAY be an intermittent open circuit in the Sensor Power & Ground Pulse, or whether the DME electronics (MOSFET) are NOT working properly to produce the Ground pulse for Injector #3, but SOMETHING is intermittently NOT functioning related to the circuit for Injector #3. Since "misfire" is measured by slight slowing of crankshaft speed on power stroke of one cylinder as compared to preceding & succeeding cylinders in firing order (as opposed to an electrical measurement related to coils or plugs), an injector fault can cause a "misfire" (P0303) on cylinder #3, just as an ignition fault can.

So the cause of your P0303 and P311B is the same: Injector circuit for Injector #3. Here is TIS circuit for your injectors, along with Installation Location:
https://www.newtis.info/tisv2/a/en/e...ection/dAB3Dk4
https://www.newtis.info/tisv2/a/en/e...xi-lim/S82VdKI

I would start by disconnecting the Connector, X6103 at the Injector (Y6103), checking for any corrosion or damage/ looseness in the pins & sockets, cleaning pins & sockets with Electronic Contact Cleaner, reassembling, clearing all codes, and seeing if, and under what conditions (Freeze Frame Data) any code recurs. ANY P-code reader can read those codes.

George

Hi George,

Thank you for the very informative response,

Yes sorry, I meant i started getting the P311B code Saturday night, once I turned the car off and back on it had gone away for that evening, Sunday I had no issues at all while driving my car all day. Monday afternoon I received the P0303 for the misfire on cylinder 3, cleared the code and kept driving no issues, Monday night I went to my buddies place and I the way back home I got the P0303 code once again and erased it and made it home. This morning while driving the half engine light came on and again P311B. I returned home, cleared the code again and decided to swap coils over since I’m limited on tools because I’m house sitting for my mom’s.

After swapping the coils over and making sure all 6 are seated correctly I took the car for a quick drive and upon WOT got code P0303 once again.

I was afraid that it would be related to the injector so I’ll have to do the steps you’re referencing when I return home. I was hoping that it would only be a fouled spark plug. This all started happening Saturday night after a huge rainfall..

[OTO335i]

Little update,

Finally back at my own house. I got home and swapped spark plugs in between cylinder 2 and 3, cleaned the connector on the harness and injector with electrical cleaner on cylinder 3. I went for a drive and im still getting the code for misfire on cylinder 3 (P0303) I'm no longer getting the P311B code and also not getting the half engine light in the dash.

All i have is a small scanner and i do not own a lap top or cable. Is it safe to say that the injector is the culprit?

Edit*
If i were to acquire a laptop, proper cable and programs would it be wise to swap injector 3 with another and code it to see if the misfire follows that injector?

Thanks again