Project M3, Part 8: The Dreaded EML Light
(and what to do about it)
We apologize for the eight-month hiatus with Project E46 M3, but we’ve been hard at work and—even though we had an issue we didn’t tell you about over the past year—the car is now running like a champ. We’ve even dyno tested a new performance part and added a bunch of tasteful exterior and interior upgrades, but we’ll have more on that soon. Today we’ll talk about the aforementioned issue that we took care of.
If you haven’t seen the yellow “EML” light on your BMW E46, it’s probably only a matter of time. It stands for Elektronische Motorleistungsregelung, and it can mean a myriad of “electronic engine power control” issues, mostly having to do with the drive-by-wire system.
Ahh, yes. The fun EML light. In Project M3’s case, when this light would come on, the car would shut itself off in a matter of roughly 3 seconds and not start back up. The engine would turn over but there would be no fuel or ignition, as if we had a dead ECU. Not fun if you're not sure what to do.
Yes, that’s the windshield fluid low-level indicator, which is empty (because I accidentally drilled a hole through it while putting on a splitter I'll be sharing with you soon). And yes, that’s also the airbag light, which seems to rear its ugly head on each of the five M3s I’ve owned. I’m just so used to seeing it that I don’t worry about it any more.
The most common part to go wrong in the EML circuit is for one of the Throttle Position Sensors (TPS) to go bad, and the one you hope to be malfunctioning is this one—the #1 TPS—which is right above the air filter. It’s just the easiest one to swap out.
The first time I had the EML light come on, it was right after our Corsa exhaust and VAC Motorsport pulleys swap, which was prior to the AEM Infinity EMS installation. At first, it was puzzling because I’d swapped out TPS #1 and the car ran well, only to have the light come back within a week or two.
When you swap out the TPS, be careful not to strip the Phillips screws, which are weak-sauce. I later replaced them with these socket head cap screws, which have an Allen head, size M4 0.7 x 25mm.
Unfortunately, after a couple of weeks the EML light would come on at times, and the car would stall again. I had hoped that the new AEM Infinity install in Part 6 would clear this, things unfortunately didn’t change. But then it drove fine for months again. So far, so weird.
It wasn’t until my wife and I took a road trip last November, 2013, from Kansas City to St. Louis (to watch Argentina take on Bosnia/Herzegovina in a FIFA soccer friendly—holy cow there are a lot of Bosnians in St. Louis!) that I figured out what was going on, or so I thought. First I’d thought we were stuck on the side of the road for good, and our weekend was ruined. Luckily, we both figured out—OK she spotted it, and wants my readers to know it—that pulling fuse #29, and reinserting it with the key off cleared the EML light (I recently also realized that pulling TPS #1 and plugging it back in would do the same trick). This trick would work, but only for 20minutes or so.