Engine dies, "Reduced Power," no start for about 3 minutes
 

Hi all,

I have a 2007 H3 with the I5. Three times in the past week or so, the car has died after popping up a "Reduced Power" message (I think there may have been something about traction before that and throwing a CEL. The first time I was actually driving, although I was slowing to go around a corner. This was maybe 5 minutes after start-up. The other two were both in my driveway immediately after start-up. In both cases, turning the ignition key will turn on accessories and all dash lights, but no start...no cranking at all, and I believe the dash lights go out when I turn to the start position although the radio doesn't (so power doesn't go out). This continues for maybe three minutes, then everything starts normally, with the CEL. The first time I read the code and only saw a fault "N/A 01/02," the second time I saw both that and a pending code Pxxxx (I forget the number, but it's PCM checksum error). Both times I cleared them and they stayed away until the next time. This last one hasn't been read or cleared yet. I noticed this last time that the air recirc and AC settings (from pushing the respective knobs) were reset to off when it powered back up...they had been on...but the trip odometer had NOT been reset.

Other potentially useful info: My battery was old and a bit shaky on start-up for the first two times. I replaced it yesterday, so this last time was with the new battery, although it hadn't had much time to charge other than the way it came from the store, in case that's relevant.

Anyone else experience something like this?

It was either your battery, and if you still have the POS OEM battery Terminal Connectors, it was those pieces of crap.

Do you still have the OEM battery terminal connectors? If so, hack them off NOW, and replace with a quality aftermarket set, like Stingers or your favorite brand.

Interesting that you say that...I do have the original terminals, in fact the positive terminal broke when re-installing the battery. Late last night and I currently have a strange mish-mash of cheap aftermarket terminal holding the original in place. It was the best I could do on short notice, but seems tight. Sounds like I should look into correcting that ASAP...

The PCM is very sensitive to slight voltage changes. Loose OEM battery terminal connectors are the #1 cause of electrical problems in these vehicles.
Change those terminals now, before you do any other troubleshooting.

I just ordered a new set. Thanks for the info!

New terminals installed. Unfortunately I trashed the "pretty" ground terminal...it wouldn't get tight enough to stay snug to the ground terminal, yet wouldn't open up enough to use a terminal shim. WTF? I ended up having to use a generic ground terminal but it seems to work. Now, who knows if this was my problem, or just a problem area to get out of the way? I guess we'll find out soon enough....

FYI everybody:
The positive and the negative battery posts are different diameters.
When replacing battery connectors, you need (1) pos connector and (1) neg connector.

Correct, which is why I specifically ordered the positive and negative versions of the terminals. It seems like they just stamped a + or - on the same part, which is a shame, because it seemed like decent quality otherwise. Looking at the reviews on Amazon, I see a few comments to that effect. I should have read them before I ordered :-(

FWIW, it stalled on me again this morning, so I gave up and took it to a dealer. Time to bend over. I just am not equipped to properly diagnose all the computerized crap, and I need a reliable daily driver. It just wasn't safe driving on highways and stuff the way it was, IMO. Lol they'll probably tell me it's the aftermarket battery terminals :D

can range from an alternator going bad, dirty throttle body, low transmission fluid...grab a volt meter and check your battery would be a good starting point...