BMW and MINI Fault Codes P0171, P0174, P1343, P1349, P1351
This answer is applicable for many BMWs in addition to the one listed below.
car year: 2001
car model: 530i
Service engine soon light came on and message Transmission fail safe program came on.The car went into limp mode then cut off. Checked codes they were P1343,P1349,P1351,P0171 ,P0174. 2nd time in the last 3 months.
The fault codes that you’ve noted are as follows:
P0171 = System lean, bank-1
P0174 = System lean, Bank-2
P1343 = Misfire Cyl-1 with fuel cut-off
P1349 = Misfire Cyl-4 with fuel cut-off
P1351 = Misfire Cyl-5 with fuel cut-off
The lean codes for banks 1 (cylinders 1-3) and 2 (cylinders 4-6) may be a result of the misfires and fuel cut-offs in cylinders 1, 4 and 5. The misfires could be ignition related and this is a good first place to start.
* What is the age of the spark plugs?
* What is the age of the spark plug to coil connector boots?
* We’ll assume that the coils are original.
* Is the valve cover gasket leaking, allowing oil into the spark plug wells?
We would suggest that you pull the coils and spark plugs (at least on cylinders 1, 4 and 5 … if not all). Inspect for oil in the wells and check the condition of the plugs and boots. If the spark plugs have over 60,000 miles, we would recommend that you replace them …. along with the connector boots. If there is oil in the wells, you’ll need to replace the valve cover gaskets as well.
After replacing the spark plugs, boots and valve cover gasket (if required), clear the codes. If the codes return, swap these three coils to three different cylinders. If the codes move with the coils, replace the coils. If the codes return on the same cylinders we’ll need to get into some further diagnostics.