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Discussion Starter #1 (Edited)
Hi all,

Probably my first post as i have always managed to find all the info i need without asking for it. 3 days ago my 1999 E46 323ci 120k miles cut out while i was stationary, then struggled to start and ran at like 1/4 power for my journey home (only a few miles). the traction control light comes on and stays on while its like this too. i thought it was battery related as i have had a flat battery once before in the 3 years i have had the car, and it did a very similar thing.

i charged the battery overnight then for 2 days it ran fine, started pefectly, but then last night it did the same thing. this time i do not think its the battery as the alternator is working, gives 14v when the engine is running and drops to 13v when switched off. it would drop to 12v before i charged it.

i have an obd2 reader and the codes it throws are:-

P0335 (ALL) Crankshaft Position Sensor A Circuit Malfunction
P1622 (BMW ONLY) Map Cooling Thermostat Control Circuit Electrical

same as the other night.

i have erased them and put the car on charge again but dont think the battery is the problem. probably some sort of sensor is playing up? if i get problems again i will start taking things to bits. anyone have any ideas? thank you.

edit:-
15-11-18 1.30pm
car is back to normal after charging all night.
i have put a spare battery on charge and will put it in the car for the next time it happens. i will swap batteries and obd2 reset it as soon as it happens and see if it fixes it. the battery in the car is only 3 years old, a bosch s5 one too.
 

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Discussion Starter #2 (Edited)
done it whilst driving tonight for the first time. engine cut out then struggled to start, then finally started in limp mode. my second battery was still on charge but i think that would have been a waste of time anyway. no way its battery related imo. same codes, P0335 and P1622.

it happens when the engine is warm and by watching youtube videos it is more likely the Crankshaft Position Sensor than the thermostat but really could be either or both. temp gauge stays in the centre, nothing obvious its one or the other.

at present i personally think its a wiring issue as 2 things electrical keep going at the same time. maybe (a) corroded wire(s) or an issue with the plugs? i better check these before anything else.

i am now going to take it off the road and start investigating the wiring, and if it looks fine move onto the sensors themselves.

i will post my findings for anyone stumbling accross this thread with the same problem(s).
 

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ok so again it works fine this morning so i decided to take it out with my obd2 scanner to try to see if one trips before another. P1622 trips first but has no effect on the vehicle, therefore it is P0335 that is causing the cut out and limp mode. its now off the road and will sort it out at the weekend. i havent let P0335 trip this time as it has happened 3 times and last time it nearly caused an accident.
 

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ive still been using it in and around town having the fans blowing on full heat and have not had any issues. keeping the temp needle less than halfway basically. the car would only trip error P0335 after the car has the needle in the middle.

i have ordered a WAHLER Thermostat (the same company that makes the genuine bmw ones), once replaced i will give it a good run and see what happens. fingers crossed i dont have to do the crankshaft sensor.
 

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Thermostat fault is because of a dying, slow stat. You said if you keep the fans on the temp doesn't get half way - it shouldn't do that. It should hold half way solidly. It's overcooling. It won't affect running.

The crankshaft sensor is your problem. When it fails the motor won't run. Fix that as a priority.
 

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i have still not fixed anything and it has been a week since ive had a cut out. still doing my heater thing. i have the thermostat now and will hopefully change it tomorrow, once i get some ethylene glycol coolant. im 30 miles away from a bmw service centre so have been struggling to find a recommended coolant. the only place in my town that has it is halfords but its twice the price it would be from bmw themselves! does anyone ever actually buy anything from those thieves? i dont! i have 2 places to try tomorrow locally before thinking about going to the bmw garage.

i do think it is the sensor causing the cut out but why is not letting it get as hot as it normally would helping? i know 100% i need a new thermostat but no crankshaft sensor failure for a week?

probably around 5 days ago i did unplug the thermostat cable and and the connectors looked as good as new. i also removed the ecu, all the cables+connectors looked mint. i then removed the ecu shell and looked at the ecu board under magnification and that too looks as good as new. i was surprised at how good everything looked! i havent looked at the crankshaft sensor connector as i dont think i'll get to it without removing the cooling system etc.

i will post again soon with an update, or if it fails again.

thank you for the advice and im pretty sure you are correct adam-- but the crankshaft sensor looks like a pig of a job so im taking the fix one thing at a time route.
 
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