I've lost it. My bmw has won. Dear P0601, eml, and asc god, help me. 1999 328i

[benjiwinters]

1999 BMW 328i sedan - 5-speed manual - E46


I will try to make this as to the point as possible. I have been searching and reading for a few weeks while trying to fix this issue.


PROBLEM: After driving for anywhere from 20 miles to 100 miles The EML, ASC, and CHECK ENGINE light all come on at once. It goes into the "limp mode" I'm sure you are all familiar with. Within a key cycle or two, the car is running great again and just leaves the check engine light. The only code it leaves is a P0601. This is how the problem goes every time. No change.


WHAT I'VE TRIED: First thing I did was clean the throttle body. Then cleaned it again after the 3 lights came back on a few days later. Cleaned it again. Lights on again. Purchased a used throttle body with warranty and installed it myself. Lights came back on. Put the old throttle body back on and cleaned the ICV right above the TB. The lights came back on. I was desperate and a friend let me borrow his throttle body and ICV since we know his is good. Installed both and the lights came back on! My friend then installed my old throttle body and ICV on his and they are working perfectly.


So, I have to assume that it is not the TB or ICV right? But everything I've read points right to it. I don't know where to go from here. Has anyone on here by any chance had this problem and a TB or ICV just wasn't the problem?

If I left anything out please let me know. Thanks.

[bmwdirtracer]

Mistake number 1 is trying to diagnose this by means of a generic p-code reader. The car needs to be hooked up to a full-on BMW diagnostic computer which can read ALL of the codes from ALL of the computers involved: the DME, the EGS, and the ABS. The correct diag computer can then perform the associated tests, and even reprogram/update any computer that needs it, if necessary.

[SeanCollins]

p0601 is a ecu checksum or memmory error iirc In fact I looked it up. you either have a serious electrical problem, water intrusion into the ECU or a bad ecu.

screenshot10.png

[tommytoyzz]

I am having this identical problem. I have a 1999 323i and it is exactly the same. I read perhaps it is the small hose/pipe, right under the plastic motor cover, over the intake manifold, which collapses and chokes the engine. I haven't checked yet, but I will maybe tomorrow.

Before I go an blame an ECS module, I will look for this.

- - - Updated - - -

In reading some more and in jogging my memory, I think it can also be the Throttle Position Sensor. I noticed recently that when switching between gears, the engine would not rev down very quickly, even though the clutch was pressed and the gas pedal was not pressed. I though it was the clutch sensor, if there is such a thing.

But now I think the engine did not rev down, because it did not receive the signal from the pedal to rev down. A faulty Throttle position sensor, or a faulty connection between the sensors and DME, will cause our problem - if that is faulty.

I was also wondering why my throttle response was a bit jerky. Seems to make sense to me that this may the culprit. Here is a similar thread:

http://forum.e46fanatics.com/showthread.php?t=620400

- - - Updated - - -

Another thing I have seen is that since it starts intermittently and then, as it gets worse, after the engine is nice and warm or has been for a while, it is easy to misdiagnose. One guy swapped out throttle bodies with a friend's car and said they both worked perfect.

Well the faulty one does work perfect, till they get or stay warm. Others, including myself, have been getting periodical asc/dcs lights for just a moment or jerky engine response. This I think, was the beginning. The reason the ASC/DCS light come on, is because that is how the DME restricts the RPMs, regardless of the gas pedal position - because it doesn't know what the pedal position is.

The DME doesn't know what the position the pedal is at either because:

1. The Throttle position sensor is worn or not working properly (In 323i with M52TU - replace entire throttle body), or
2. The Wire loom or connectors are shorted/frayed/connectors contaminated, etc...(Replace the engine wire harness) - not too difficult DIY

The throttle position sensor is inside the throttle body, that's why if the sensor is bad, we have to replace the entire throttle body.

I had a similar problem with my VW with the crank position sensor. It stopped working, but only at a certain temperature, allowing me to drive for a while before the engine got warm and then the sensor and engine quit.

[benjiwinters]

Hey guys, I thought I would update this incase someone else runs into the same problem. In the end, it will most likely be a throttle body or bad wiring to the throttle body 90% of the time. In my case however, after you have checked and tried both of those things, it ends up needing a computer. It is now fixed. Computer was around 1100$ and the labor to install/program was another 150$.

I tried everything else. In the end there is no hope.

[tommytoyzz]

I changed out the MDK and the engine wire harness and so far so good. My EML, check engine light and ASC lights would all come on and the car would go into limp mode. I read in other posts that often it is the wire connector(s) that go bad, get contaminated, etc....So I changed both to be sure, even though the fail codes suggested the MDK only (throttle body on M52TU engine). I got mine from an engine with 75,000 miles, while my original MDK and wire harness have traveled 190,000miles.

The newer wire harness looked much better than my old one.

[Milsom1]

Had this code come up on my 323ci and had limp mode kick in to the point I codnt drive the car more than 2miles after reseting the code before coming back on, I replaced inlet, throttle body, pipework sensors and still had the same issue. After some info I replaced the throttle cable as it was stiffer than usual and found that to be the answer 😅 the cable was to stiff to allow the throttle body to close properly and would throw out the position reading creating a p0601 throttle body issue 'check sum'.

[jpezz333]

I have a 1999 528. It has 264k miles. I have replaced the throttle body every year for the last 3 years with a used one. I have code p0601 now and the car is in limp mode again. It seems like the same symptoms as previous throttle body issues. Is anyone else having to replace throttle bodies this frequently? I understand that I am buying used ones so don't expect them to last forever but it seems odd to be on the 4th throttle body in 4 years. Any ideas if something could be causing the throttle position sensor to fry? Has anyone heard of a way to rebuild or replace the throttle position sensor on these since they are built into the throttle body?

[jclausen]

Eml=engine malfunction light=throttle body or wiring about 90% of the time.

[ross1]

I have a 1999 528. It has 264k miles. I have replaced the throttle body every year for the last 3 years with a used one. I have code p0601 now and the car is in limp mode again. It seems like the same symptoms as previous throttle body issues. Is anyone else having to replace throttle bodies this frequently? I understand that I am buying used ones so don't expect them to last forever but it seems odd to be on the 4th throttle body in 4 years. Any ideas if something could be causing the throttle position sensor to fry? Has anyone heard of a way to rebuild or replace the throttle position sensor on these since they are built into the throttle body?

Did you read post #7?

[Gordon33]

I just had the water pump.. belt and thermostat control replaced.. one week later I got the dreaded code you guys are mentioning...p0601. My shop says it's the throttle body that needs to be replaced. They want another$1300 to do the job which they don't know if it will actually fix it.. I'm pulling my hair out as my 2000 bmw 528i has 240k miles on it but was rebuilt at 217k. Also rebuilt the suspension and heads machined. All said.. I've put over 10k into bringing this car back to life. Any suggestions?

[328 Power 04]

I just had the water pump.. belt and thermostat control replaced.. one week later I got the dreaded code you guys are mentioning...p0601. My shop says it's the throttle body that needs to be replaced. They want another$1300 to do the job which they don't know if it will actually fix it.. I'm pulling my hair out as my 2000 bmw 528i has 240k miles on it but was rebuilt at 217k. Also rebuilt the suspension and heads machined. All said.. I've put over 10k into bringing this car back to life. Any suggestions?

Are you acceptably OK at wrenching?