b2ke

My mom owns a 2000 C4 with 38k miles which she never drives. It literally sits in the garage covered and I warm it up at least once a month for her. I think she has driven it no more than 10 miles. I won't go into detail on why she owns the car but yeah it just sits until every now and then I drive it or warm it up. The C4 is basically my "turn key and go" car when my daily (2002 BMW e39 540i) is down and requires work. Currently my BMW is down because I need to replace the broken timing chain guides, a notorious problem for the v8 motor of that generation. And being a student, I have not had time to address that issue so I have been driving the C4 for well over a month now. I plan on fixing my car at the end of the month during spring break/this entire Covid 19 "shut down" period.

Anyway, the other day I cold started the C4 and drove it out of my driveway. After only a few houses down the check engine light started to flash/blink for a few seconds. I then stopped the car, with the engine running, to listen for any noise and see if the check engine light will come back. No weird sounds, vibrations, etc. and the light did not appear again. I then backed the car back into my driveway and scanned it with a generic OBII scanner. The scanner read no codes.

I drove the car again today about 15-20 miles to run errands and it was fine. Check engine light has yet to reappear.

So here are a few questions...

I'm not familiar with the 996 as I am with the BMW e39 so I'm unsure where to go from here. My question is what do you all suggest my next steps be? OBD2 scanner isn't showing any codes and the car is not exhibiting anything out of the ordinary but I definitely don't wan to take any chances with this car. I've got 7-8 years of experience wrenching on my BMW so I'd like to think I am capable of tackling most jobs. I've also been on the BMW forums for the same amount of time, 7-8 years, so I know these forums are great places full of information and great people. And yes I know the search feature is available for most common problems but I figured I'd make an introduction as I'd like to join this community as well.

Also, for my BMW I have a K+DCAN ($20) cable to connect my BMW to my laptop where I use BMW specific diagnostics/coding software (INPA) to scan my car. This software reads BMW specific code and real time engine data. Is there a comparable software like that I can use for the 996?

Here is a picture of the car in question.



Here are a couple shots of my BMW. One being a progress shot of the engine tear down.

dporto

Nice looking car! Why's the spoiler up when the car is parked? A flashing CEL is not a good thing (it means shut the car off and flat bed it to service immediately). The fact that it went away and didn't come back yet is troubling as well. In any case, you shouldn't be running/driving the car until you figure out why the light came on in the first place. The only theory I have is that you might have some rodent damage to wiring as the car has been sitting for so long. That would be the best case scenario... ** The E39 (M5 Look) is an awesome car! My son had one early on in his car ownership (he's owned more cars in the last 10 years than I've owned my entire life ). I loved driving that car (540i with manual transmission), and we did a lot of work on it together... Good luck with both!

srop816

It's ashame that beauty is just sittin around. good luck

billh1963

Seems like lots of BMW guys wind up in 996's. It's great that you work on your own car.That helps a lot in terms of learning to troubleshoot, understanding how an engine operates, etc. However, very little of what you know about BMW engines (except obvious basic mechanical knowledge and comfort with using tools) applies to the M96 engine trouble areas.

Buy a durametric to read the codes.

Watch this video for some basic tips.

Ahmet

Flashing engine light means driving the car can cause damage to the catalysts. No codes obviously means nothing stored. Durametric is a tool available that you can use to glean more information, look at live sensor outputs, test activations of various components, etc.

The flashing light was probably caused by a misfire from a bad coil/old plugs. I would get ready to do that in your shoes.

Good luck

motoo344

Nice cars, the 996 is a car that needs to be driven! The Durametric seems to be the go-to tool for reading these cars software and there is a lot of good info on the forum.

mattie_k

Give it a good once over, check oil and coolant. But yes could be it misfired.

4Driver4

Running it at idle is a horrible idea. If you start it, drive it until fully warmed up.

Turbodan

otherwise just let it sit. IMO starting it every month is not helping her.

jobyt

Yep, and I imagine the oil hasn't been changed on a regular time (vs. mileage) schedule. I'd do that first and cut open the filter.

b2ke

Thank you all for the responses.

The check engine light hasn't appeared since the time it flashed so it is making investigating the problem harder because my OBD2 scanner can't scan codes not stored. I would love to purchase the Durametric to assist me, but I am unfortunately not in the right position to as I'm a college student with limited funds. And I am currently working on my own car. If it were my daily then I would not hesitate to and I will definitely keep the Durametric in mind for the future.


Nevertheless, the car will not be driven until I first inspect the plugs and coils because the notion of a flashing CEL meaning misfire makes sense to me. Some of my research tells me the coils could be the culprit because they are so close to the exhaust and are exposed to high temperatures. So I assume if this is the case then would it be wise to replace all 6 coils instead of just replacing the cracked ones?

As for warming up the car for my mom about once a month, I do drive it to warm it up rather than start it and let it idle. I can only do this once a month because she lives 25 minutes from me and it is hard for me to make time to drive over there. Again, I won't go into much detail but she isn't in the best position to drive it herself (health issues) and almost refuses to. The C4 is also 6-speed which scares her even more to drive it so even if I had her warm the car up once a month it would be her idling it rather than driving it. She hasn't driven a manual car since the early 90's before I was even born.

I changed the oil about 500 miles ago, the oil and oil filter looked clean with no metal. I don't know when the last time the oil was changed prior but I believe its been 3-4 years since it has been changed. Yes I know, that's quite long over due but also the car probably hadn't been driven over 1k miles in the past 4 years since the time she acquired the car.

dporto

^^ Ok, so do some reading up on oil changes (without getting too far into the weeds on oil types) and you'll see that just starting the car/short drives are really bad for the oil (in addition to other things). It sounds like this car has some sentimental value to your mom, so there are a few things you can do to keep it healthy. 1) Buy a Durametric - either get her to buy it, or split the cost with her. You may even be able to get a used one with only one Vin left for around $100. This will help you diagnose problems and fix them before they become bigger. 2) Change the oil at 6 month intervals even if it's got barely any miles on it - the oil fouls easily from sitting, idling and short trips (It gets fuel and water in it and becomes acidic). If it's being changed out with barely any miles on it, you don't have to use super expensive oil - Mobile 1 in the Big jugs ($25 for 5L at Walmart should be ok - just make sure it's the Euro Spec stuff). I wouldn't recommend this oil if you're putting real miles on it, but if it's basically just sitting around it should be fine. If it kills you to be dumping lightly used oil, put it in your/her/your neighbors lawn mower (that oil hasn't been changed in a while I'm sure). Good luck

TexSquirrel

Durametric is the Porsche equivalent of the BMW Bavarian Technics.
I suggest you get one for your Mom's 996.

GarrettSR5

An M96 as a back up to an M62

Living on the edge

GarrettSR5

As others have said, a flashing CEL is a serious warning to immediately stop the vehicle and shut it down as damage to the emissions system is immediately possible