ThatSalesGuy

Was driving today and saw the CEL light start flashing. Trying to get off the freeway and to pull over, I see a bunch of smoke coming from the engine bay. A couple seconds later the car shut off and wouldn't restart. Luckily by the time that happened (less than a minute for all that) I was able to get pulled to the shoulder.

got the car towed home and ran the codes for CEL and it's a plethota.

P0301
P1225
P1227
P1230
P1228
P1226
P1229
P1115
P1117
P1118
P1119

2000 911 C2 6 speed
97k on the clock

Eek, gotta see what these all are. And try to determine what would cause that and hope they was nothing additional to find.

And, did I mention the tow truck blew a tire while taking the car and I home?

Mbren1979

I would first see if you could find the source of the smoke. That could possibly be the root of all the issues.

P0301 Cylinder 1 missfire
P1225 Cylinder 1 fuel injector - below limit
P1227 Cylinder 2 fuel injector - below limit
P1230 Cylinder 5 fuel injector - below limit
P1228 Cylinder 4 fuel injector - below limit
P1226 Cylinder 6 fuel injector - below limit
P1229 Cylinder 3 fuel injector - below limit
P1115 Oxygen sensor heating ahead of TWC - Bank 1
P1117 Oxygen sensor heating after TWC - Bank 1
P1118 Oxygen sensor heating after TWC - Bank 2
P1119 Oxygen sensor heating ahead of TWC - Bank 2

It looks as if the one major things these all have in common is a rely labeled "Ignition/Oxygen/Injector Relay" located on relay support 2 and is powered by fuse C2 which is a 30 Amp

Maybe that may give you a starting point in your Diag?

ThatSalesGuy

definitely a place to start
what would cause that fuse to blow?

Mbren1979

A short anywhere in the circuit. That's why helping to identify the smoke may point you in a direction. Crappy example - but lets say you pop the hood and notice the serp belt broke. it would be possible that the belt tore up some wiring at the moment it snapped which would cause a short and all these codes. Not saying that is your issue, but the cause of the smoke is either your beginning of the failure or a side effect of the failure. either way, it gives direction - hopefully.

ThatSalesGuy

well, the fuse is definitely blown.

now to figure out why. Not sure where to even start at this point.

not too long ago, found a small coolant leak from a hose. Replaced that and all was good. Didnt notice any more leaks. Could a small leak like this somehow cause the fuse to go? Maybe there is another one, car is 18 years old.
The coolant level in the overflow is 3/4 now, so somewhere its leaking or evaporating again.

Mbren1979

Well, I would start with a good visual inspection under the hood (what little can be seen at least). i would look at the O2 sensor wiring and make sure it all looks in tact and not damaged (melted on the exhaust). If a visual inspection looks o.k. and you can't identify where the initial smoke came from, pop another 30 amp fuse in and see what happens. If it dosen't blow immediately - that will suck because the problem is intermittent and will be a pain in the butt to diag. If it does blow, then a multi meter and diagnostic will have to start. You may also want to swap the relay with another identical one too. Euro cars are known to have crappy relays that can short internal.

Ahsai

Good advice. Instead of a regular fuse, you may want to use a smart fuse instead. When the fuse blows, it will light up (built-in LED). If the fuse blows again, I would start unplugging each O2 sensor one by one and see if the LED goes out. If it does, it's whatever you just unplugged creating a short. You can then unplug the two big round canon connectors one by one in the right side of the engine bay.

ThatSalesGuy

if that LED fuse blows, wouldn't the metal connector piece inside it melt? Therefore pulling the shorted O2 sensor wouldn't make a difference as the circuit is already compromised at the fuse.

what are the cannons you speak of in the rights side of the engine bay?

Would it be safe to pop another fuse in without knowing the reason it blew in the first place? Is it common enough that a fuse just as lived its life and fails without cause?

thanks

Mbren1979

I was waiting for Ahsai to chime in. His knowledge and help is invaluable. Yes it is safe to pop another fuse in. Just don't throw a bigger one in hopping that will fix it. The fuse is designed to blow if the problem still exists. That is its whole job in life. And no - fuses don't have a life cycle. There is no moving parts to wear out.

ThatSalesGuy

I will try it, just didnt want to cause more issues. Obviously something had to cause it to go, frustrating to try and find that.

I was more wondering if a fuse generally just blows and is the cause of the short. Maybe defective or something.

MattBurns

I would pull cylinder 1 coil and inspect it closely. The reason I say this is that your flashing check engine light indicates a misfire. You have a cylinder 1 misfire code also, but no other misfire codes, but fuse C2 powers all the coils so if the misfire code set from the fuse blowing, you should have codes for all 6 cylinders misfiring. My money says the #1 coil is shorted and that was the start of your issues before the overloaded 30 amp fuse blew and set all the other codes and causing the car to shut down.

Mbren1979

Very good point. My wiring diagram agree's with this statement. An easy confirmation to a fried coil could be if the fuse continues to pop when installed (or use smart fuses as Ashai described), disconnect coil #1. If the short goes away, there's your problem.

ThatSalesGuy

good idea. I will have to look at that tomorrow most likely. To confirm, cylinder 1 is driver side furthest to back of car?

Got to find a way to get the car from the driveway into the garage. Dont want to jack it up on an incline.

the relay itself seems to function properly when I pulled it out and tested it.

MattBurns

If the relay wasn't working the fuse likely wouldn't be blown. I guess it's possible there is a short between the fuse and relay, but in my experience that is rare. You could verify by pulling the relay and installing a new fuse. If it doesn't blow your short is on the other side of the relay which is most likely the case.

lowpue

Wow...watching this realtime diagnosis is really great to see. THis is a great example of the power of this forum. I am not even the one this is happening to and yet...Thanks guys and TSG, hope its as easy as it seems.