Code P1500: Idle Control Valve (Again)?

[freethrowdunk]

Update in post #15

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The car's been treating me well lately ever since I reinstalled a fully functioning (rebuilt) ABS unit.

Yesterday during the drive home on the highway the dreaded 'Engine Failsafe Prog' message appeared in the cluster and affected acceleration during low RPMs immediately. No check engine light appeared.

I exited soon and scanned for codes, and sure enough the P1500 code appeared related to the ICV being stuck open.

Over a year ago I had this issue and it was blatantly obvious that something was amiss with the ICV: I noticed, on a few occasions, a sluggish idle. The check engine light would also illuminate when the 'Engine Failsafe Prog' would appear, and the same P1500 code was stored.

We took out the ICV then (sure enough it was stuck), cleaned it thoroughly, and the problem went away.

Question 1): Could it be that I did not clean it as thoroughly as I think I did? Hence why the problem has resurfaced just a bit over a year later? Also, I have an aftermarket air filter made by AEM. It's their DryFlow filter that does not require any oiling. I maintain it very well by cleaning it using their solution at least twice a year and it's in like-new condition as it is. So question 2): Could it be that these filters are not as good as they're advertised to be--AEM boasts something along the lines of manufacturing filters that are capable of filtering more than 99% of particulates? And thus I should revert back to the stock air box unit if I wish for a more long-term solution to this problem...

Lastly, could the ABS unit in any way be causing this issue? Part of the P1500 code does read something about the wheel speed sensor, and that is definitely related to the ABS. I ask because the company that rebuilt my ABS unit (have a thread on here about it) did a shoddy job the first time around and didn't repair it well.

In any case, I have already ordered a brand-new Bosch ICV along with the two rubber connecting boots, if by chance they're worn out due to age. Might as well change these along with the ICV, they're not expensive parts.

[edjack]

Cleaning an ICV sometimes does not work.

[freethrowdunk]

Cleaning an ICV sometimes does not work.

I see. This may be one of those instances.

[bimas]

+1 on a dead ICV. Sometimes, it's just dead. With the ignition key turned, you may hear a buzzing noise from the engine compartment when you lift the hood. Sometimes you won't. But if you do, the ICV is probably broken.

[freethrowdunk]

+1 on a dead ICV. Sometimes, it's just dead. With the ignition key turned, you may hear a buzzing noise from the engine compartment when you lift the hood. Sometimes you won't. But if you do, the ICV is probably broken.

Hmm. I've heard this buzzing noise you speak of for a long time now, like, for years since owning this car. Surely it cannot have been broken this long. Maybe it's another buzzing noise you're referring to/the one I hear.

[EURO E39]

I also hear this buzzing from my ICV with key in "on" - not started position...and it's a brand new (from Ebay vendor...could it be bogus?) Bosch ICV..
Dealer says that's the cause of my high idle (750 rpm) and vacuum leak sound...and 12 mpg...
I drove for a few days with the ICV unplugged...less vacuum pitch sound and much more responsive throttle..MPGs still crappy.

New Seimens MAF in bound...guess I try another ICV from better vendor...

[freethrowdunk]

Roughly 600 miles and a mere 3 months later (the car isn't driven much) after replacing the ICV with a new OEM Bosch one, same 'Engine Failsafe Prog' message appeared in the cluster tonight; no check engine light.

Nevertheless I read the codes and during the first instance there were three, one of which was the same P1500. I forget the numbers of the other two but something about 'bank 1 running too rich' and 'bank 2 running too rich.'

I cleared the codes and went for a short drive. Sure enough the 'Engine Failsafe Prog' message appeared again but when I looked at the codes this time, there was only 1: the P1500. Nothing as far as the ICV being stuck open or closed
(something I have seen previously), but something regarding what I think was the ICV, another regarding vehicle speed manuf., and lastly one on auxiliary inputs--whatever that means. I should have taken a picture of the reader's screen.

In any case, where to start diagnosing this? Again, I have changed the ICV along with the rubber boots, all with OEM ones. I'm beginning to think it's the CAI that's the culprit and that I should replace it with the stock factory air box.

Thoughts?

[edjack]

Dump the aftermarket filter.

The ICV should buzz with the KOEO (key position 2). You can feel it.

[freethrowdunk]

Dump the aftermarket filter.

Fair enough. You mean the CAI altogether, yes?

- - - Updated - - -

Dump the aftermarket filter.

The ICV should buzz with the KOEO (key position 2). You can feel it.

It does buzz. I've been hearing a buzzing sound from that region since I've had this car dating back to '06. The old one buzzed and so too does this new one.

[rf900rkw]

Bad MAF.

[MrTeeThyme]

With the car idling, turn the a/c on. If the RPMs increase, that should be an indication your ICV is functioning properly.

[rf900rkw]

That is not a valid test for this situation. Really, that is not a valid test for the M52TU or M54.



you need to understand that replacing the part named in a code does not a mechanic make, and often will not fix the problem. Buying a more expensive part from the high end boutique won't fix it either.

You need to understand how the M54 intake system works and the IAC's role in such.

You need to understand the code, what prerequisites are required and what tests must fail to set the specific code.

You need to understand the related codes, tests, and what passed and what did not.

Then finally, once you have all that, you can look at the entire system and make an educated diagnosis.


The BMW training manuals that explain how the system works are out there on the interwebs. The IAC is passing all electrical tests (P1502, P1503, P1504, P1506, P1507, P1508). The IAC performance is good, it hits the targeted idle speeds at all times (P0505). The "only" IAC related code is the P1500;

Target torque does not match real torque. Real torque is higher.

The assumption they made was the cause would be the IAC sticking open. But that is certainly not the only possible cause. The "real" torque is calculated from the MAF reading. If the MAF is reading too high at low load (but above idle) conditions, that torque will be skewed high and the P1500 could be set. This is fully backed by the rich mixture codes that were hand waved off.

[freethrowdunk]

That is not a valid test for this situation. Really, that is not a valid test for the M52TU or M54.



you need to understand that replacing the part named in a code does not a mechanic make, and often will not fix the problem. Buying a more expensive part from the high end boutique won't fix it either.

You need to understand how the M54 intake system works and the IAC's role in such.

You need to understand the code, what prerequisites are required and what tests must fail to set the specific code.

You need to understand the related codes, tests, and what passed and what did not.

Then finally, once you have all that, you can look at the entire system and make an educated diagnosis.


The BMW training manuals that explain how the system works are out there on the interwebs. The IAC is passing all electrical tests (P1502, P1503, P1504, P1506, P1507, P1508). The IAC performance is good, it hits the targeted idle speeds at all times (P0505). The "only" IAC related code is the P1500;

Target torque does not match real torque. Real torque is higher.

The assumption they made was the cause would be the IAC sticking open. But that is certainly not the only possible cause. The "real" torque is calculated from the MAF reading. If the MAF is reading too high at low load (but above idle) conditions, that torque will be skewed high and the P1500 could be set. This is fully backed by the rich mixture codes that were hand waved off.

Wow, what a detailed response! Thank you very much. I will be purchasing a new MAF soon.

[MrTeeThyme]

That is not a valid test for this situation. Really, that is not a valid test for the M52TU or M54.



you need to understand that replacing the part named in a code does not a mechanic make, and often will not fix the problem. Buying a more expensive part from the high end boutique won't fix it either.

You need to understand how the M54 intake system works and the IAC's role in such.

You need to understand the code, what prerequisites are required and what tests must fail to set the specific code.

You need to understand the related codes, tests, and what passed and what did not.

Then finally, once you have all that, you can look at the entire system and make an educated diagnosis.


The BMW training manuals that explain how the system works are out there on the interwebs. The IAC is passing all electrical tests (P1502, P1503, P1504, P1506, P1507, P1508). The IAC performance is good, it hits the targeted idle speeds at all times (P0505). The "only" IAC related code is the P1500;

Target torque does not match real torque. Real torque is higher.

The assumption they made was the cause would be the IAC sticking open. But that is certainly not the only possible cause. The "real" torque is calculated from the MAF reading. If the MAF is reading too high at low load (but above idle) conditions, that torque will be skewed high and the P1500 could be set. This is fully backed by the rich mixture codes that were hand waved off.

The test I suggested is from the Bently manual. The way they discuss it suggests that if it passes the test, it's good, but it's not necessarily bad if it fails.

[freethrowdunk]

Update and still perplexed over this:

I don't drive the car much (as a matter of fact, I've only put about 7,000 more miles onto the ODO since making this thread). But the other night, while driving about 20 miles round trip, this same P1500 code reared its head...three times. Of course, it was accompanied by the "Engine Failsafe Prog" message. I cleared it with a reader all three times and haven't driven the car since. What's most frustrating in all of this is that there doesn't seem to be any rhyme or reason behind its occurrences: I can drive for months, sometimes considerable distances on the highway, without it taking place, only then to have it occur within short periods of time in, say, one night.

Here's what I have done to the car as they pertain to this issue and having heeded some of the abovementioned advice since making this thread:

1) At around 45,000 miles, I replaced the MAF with a new OEM Siemens/VDO one.

2) At 46,018 miles, which was on June 14, 2015, I replaced my silly intake with all the OE components there.

The problem seemed to have been taken care of shortly thereafter but this same issue (the same code) was thrown a couple more times, IIRC, since the CAI was removed and recently, about a week ago, as described here.

Thoughts?

[QUITE UNIQUE]

Hello!
Did you ever find a true cause for this? Ive been having the same issues for a few years now.. For long i thought relocating the IAT (to the air box, tip from Ess Tuning) did the trick, but the dreaded P1500 came back this year again… I too have changed the ICV, MAF, Throttle Body, all hoses are good, Connections look fine, no CAI...
It happens at random. Works great one day and then when you least expect it it goes in to EML mode + ESP light and you have to restart and hope it doesnt come back for a few miles/Days..

My car is supercharged with the ESS twinscrew 1, but the problem seem to occour with or without this mod, since ive read many threads about the exact same problems..

So, does anyone actually have a solution?

[E39 Newbie]

Just for the record, here are the conditions that cause a P1500 or P1501, taken from ProDemand.com. The reason for the code is a change in the calculated engine load (IAC valve - MAF). The change has to be greater than 53nm. This is only triggered when the engine is at greater than 1600 RPM, less than 0.6 degrees of throttle opening and the IAC is between 4% and 99%. Should the calculated load "suddenly" increase by greater than 53nm the error is triggered. Two times and the SES light is illuminated.

This ties in nicely with what rf900rkw posted above.