No start, codes p1434, po37o, p1727

P1434 - BMW speak for a large EVAP leak. Could be a bad fuel cap or similar. Will not cause a no start.

P0370 - Crank sensor optical unit. Wrong count. This sensor counts the teeth on the crankshaft and references the number it is supposed to count. It means the sensor is not faulty but that it is getting a wrong count. A common cause for this is the sensor not being seated properly. If it has a gap it can vibrate and generate a misread.
If no gap then it may be that the wiring to the sensor has an issue. Check the connector and the harness to see if there is damage or corrosion. This code will cause a no start.


P1727 - Cannot find this on the BMW code chart for that vehicle but BMW does list it as a CAN bus error for other models.

Thank, I bought OEM crankshaft sensor 13 62 7 639 278 with a adapt harness, the one came off the car is bigger than the I bought. I will order one like just like the one I removed, car is not firing. Thanks again.

That is a fun thing with BMW, they change parts around like making a stew. I have had times where it took four tries and sending pictures of the part on the car to get the correct part. Hope you get the correct part this time.

Yes, I hope this is the right crankshaft,this sensor has BMW printed it. It suppose to arrive May fifteenth or twenty ninth. I will get back to you soon.

We will be here awaiting your response.

Hi Steve, I received the crank shaft sensor just like the one came off the car but I still get a crank but no start. Do you have any other ideas? Thanks again.

Does it still show the same codes?

Yes it is showing the same codes and not firing from the spark plugs and coils.

Okay, take a look at the picture and you can see the crank sensor wiring.
Brown goes to ground, yellow is the bias voltage from the computer and the black wire is the signal.
Use a volt/ohm meter and check if you have a good ground on the brown lead, Then see if you also have good power feed on the yellow. (Should be either five volts or battery voltage). If either one is missing or wrong it could cause the sensor to misread.
Beyond that you could use an oscilloscope to look at the actual crank signal. And possibly pull the sensor and look inside to see if the lobes are okay on the crankshaft.
If those look okay then you would want to have the ECM checked as it controls the ignition.