Engine Mechanical problem
1998 BMW 325 6 cyl Two Wheel Drive Manual 160k miles
My check engine light has recently come on. I tried erasing the stored code by pulling the positive on my battery for a few seconds. Check engine light remained on directly at start up. I was wondering if there is a way to get the codes from the Data Link Connector without having a Peake or OBD or other diagnostic tool. I have a suspision that this is possible, because unknown by many, I know a way of simply reseting the oil service and inspection service lights without having a tool at all. Just some common things I could find around the house.
There must be a way. I'm thinking that if you ground a certain terminal (or several) in the data link connector and then turn the ignition to position 2 that the check engine light will blink a series of codes with pauses, short blinks, and long blinks or something to that affect. What are your thoughts?
Also, my car has been sucking down more coolant then usual, maybe this will help.
Pressure test the cooling system, sounds like the problem with the coolant loss might have something to do with your check engine light, also when was the oxygen sensor last replaced?
March, 8, 2008 AT 11:40 AM
It's not really " sucking" down the coolant. But I do have to a small amount in there like twice a month, which is much more often then I've ever had to. Yes, I think its very possible the coolant issue is related to the check engine light.
Where is the coolant going? Because there is no puddles or any sign of coolant dripping under or in the car. Is it mostly evaporating?
I'm not quite sure when the last time the o2 sensor was replaced. The car has a little over 160k miles on it now, so I would imagine the last time might have been at the 100k miles service. Doesn't this vehicle have 2 o2 sensors?
March, 8, 2008 AT 11:07 PM
Coolant does not evaporate. The M54 motor actually has 4 O2 sensors, just the pre-cat sensors are for fuel trim. Get the car scanned and let us know what is there.
March, 11, 2008 AT 4:54 PM
I scanned it with my OBD II tool. The only code came up as a possible misfire in cylinder 1. I then pulled the plug out of cylinder 1, cleaned it real good, replaced it, erased the fault code, and check engine light hasnt come on sinse.
I still dont get why the coolant would be doing that, especially if the scanner didnt read a fault in the coolant system. Any thoughts? If it gets worse, should I have it pressure tested?
Should I still be replacing my O2 sensors? How many of them? And which ones?
March, 11, 2008 AT 7:17 PM
The last item mentioned was should you replace the Oxygen sensors and the answer is if they are doing their job and there is no fault code for them then no, they do not need replacement, however, BMW recommends replacement intervals of 100k miles, I have seen O2 sensors doing fine at 160k miles and I have seen them " fail" much sooner. If you do replace them, then just the pre-cat sensors and not the after-cat ones. You would be wise to pressure test the cooling system and if the componants are as old as the car you may wish to replace them as the plastic componants can and do suffer from electro-mechanical degradation and from thermal cycling leading to a possible catastrophic failure of the cooling system. Please repost if any other assistance is required and good luck!