MAF sensor

[farmall57]

Wife called from 5 miles up the road, says our 03 LS w/70,000mi just shut off, won't start. So I head up there and find it will start every time, run about 1 second and die, no code is set. So we pull it home and I get to searching on the LS forum for ideas. I find a 2011 post from joegr (thanks) about the MAF sensor, so I go out pull the plug on the MAF and it will start and run, plug it in and it starts and dies. Check engine light came on after I ran it unplugged, I took it up the road with the MAF unplugged and it ran fine but displays limp mode error. So a 50 mile run to NAPA and the new one fixes it, wish I'd have known to unplug it before we pulled it home, but maybe someone will read this and it might save them a tow.

 

[joegr]

If you kept the old one, look closely at the thin exposed bare wire. Does it have a bug or some gunk on it? If so, clean it off with some MAF safe cleaner spray and you will have this one as a spare. Also, it the wire did have something on it, check the filter and the connections to it to find out where the dirt is getting in.

 

[farmall57]

You are correct. It had a PowerPro air filter in it. When I took the cover off I could see a bit of insect material in one corner on top of the filter. The glue holding the pleats of the filter had failed along several of the pleats along the edge. There was bug material in the MAF sensor, now I'm wondering how long it's been that way and how much crap went thru to the engine. It's got a good WiX filter in it now.

 

[joegr]

I've been using WiX for a while now.

 

[Michaelait]

A dirty MAF sensor can cause many problems. In my 2005 V8 LS I kept getting engine safe mode errors relating to the throttle body. It had nothing to do with the throttle body, it was a dirty MAF sensor. I sprayed it good with MAF sensor cleaner and it cleared those error codes and the LS is fine.

 

[joegr]

...It had nothing to do with the throttle body,...

Yes, as far as the throttle body itself not having a problem, but that's not what the message or code ever said anyway. What it was telling you did involve the ETC system.

You were getting ETC (Electronic Throttle Control) failsafe warnings, and these were correct. It was telling you that it couldn't use the normal ETC strategy because that required good MAF readings. Without good MAF readings it had to switch to an alternate (backup) ETC strategy. You can also get an ECT warning and a different backup ETC strategy for certain ABS failures, since the primary strategy needs to know what speed the car is going, and the ABS tells it that.

The ETC system is a lot more involved that just the throttle body and the gas pedal.