BLBncsu

Hello all, I just pulled multiple codes off the car thats triggering the SES light which I need to fix to pass inspections.
I've done some searching already but could use further advice on each code.

P0420: I plan on swapping side to side the post-cat O2's to see if its an O2 sensor or not.

The other 3 codes I'm lost on: I've read it could be a fuse, it could be a dirty MAF, or some vacuum leak or intake elbow leak/tear.
Any suggestions on how to tackle that?
I don't have a scanner for more detailed info. Also what is the best way to clean the MAF (can of compressed air, swabs with denatured alcohol....).

I reset the codes and drove about 30 miles hwy today and no SES light came on. Car seems to run just fine with expected fuel mileage.

Thanks all.

Injuneer

You clean the MAF sensor with "MAF sensor cleaner".... available at any auto parts store.

P0100 = Static MAF sensor frequency. The 97's often have a problem with the pink wire that supplies 12V to the sensor breaking inside the harness bundle. With key on, pull the harness connector off the MAF, and measure the voltage between the pink wire and the black/white wire. Should be 12V. If you have 12V, its probably a faulty sensor. Borrow a known good sensor from a friend.

P0171 = Bank 1 lean.
P0174 = Bank 2 lean

Since is affecting both sides, it could actually be running lean. Could be related to the MAF sensor, or maybe you have a huge tear in the rubber inlet elbow, and most of the air is bypassing the MAF sensor. Or maybe your fuel pressure is too low.

BLBncsu

Thanks for the response. I will take a look at it tonight and measure the voltage. If for some reason the wire is broken inside the harness what would be the best way to replace it? Don't really have any other "car" friends around so does any MAF sensor work to check or is it LT1 specific.

Any chance any of these codes is also what is throwing the P0420 or is that unrelated? Thanks.

BLBncsu

A follow up I could use some help on please.

So after I cleared the codes and I drove home got the SES light and the only code pulled was a P0174 so far.
- I cleaned the MAF tonight, very dirty it would seem.
- Checked the MAF connector and it had 11.8V, jiggled the harness a lot but it stayed constant and never dropped.
- Checked the intake elbow for tears/holes but found none, all seemed good.

Did my best to check the various vacuum hoses for cracks but didn't immediately see any. Started the car (it was cooled off) and heard the same noise I've heard for a very long time which is a very noticeable "sucking" sound coming from the front of the drivers side of the engine up near the "injector" area. Now when I say I've heard it for a while that means years.

I'd appreciate any help or advice on what to look into next? Thanks all!