Serious misfire problem on 2004 Vue - CEL flashing
 

Hey everyone! I'm new to the forums and hoping to address an issue with my wife's 2004 Saturn Vue.

This has been happening a while now. Check engine light is on and every so often the car will begin to misfire, the check engine light begins to flash, and the car is extremely sluggish.

We took the car to a trusted mechanic who believed the issue was a dirty throttle body. Well, after he cleaned it, reset the CEL, test drove it a few times and was convinced the issue was resolved, we came to pick up the car. Immediately after driving the car out of the lot, the CEL started flashing again and we were back at square one.

He looked at the car for another day and couldn't get the car to show symptoms so he recommended we take it to the dealership.

I'd like to repair this myself, so I've just ordered a manual for the car, but in the mean time, has anyone had any experiences like the one we are going through? Is this an issue with the ignition coil?

Here are the codes the car was throwing:
PO133 O2 SIGNAL SLOW BANK 1 SENSOR 1
PO171 FUEL SYSTEM TOO LEAN BANK 1
PO172 FUEL SYSTEM TOO RICH BANK 1
PO300 ENGINE MISFIRE DETECTED
PO420 CATALYST EFFICIENCY LOW BANK 1
PO455 EVAP SYSTEM LEAK (LARGE)

Thanks so much in advance for all the help!

Peace,
Andy

Andy,

Stop double posting.

P0133 sounds like front O2 sensor is bad.

P0171 and 0172 sound like PCM is adjusting the air fuel mix all over the place since the front 02 sensor is misbehaving

Misfiring could be as simple as plugs and wires--i'd check those first. Fuel mixture issues might also be contributing. Or other things....

Would ignore the 0420 Cat code till we get the other things straightened out -- if the front O2 is bad the comparison of front to back is meaningless for now

P0455 evap system leak -- someone else chime in here -- not my cup of tea.

After someone weighs in on the evap code (and if their advice doesn't contradict my line of thought), I'd go swap out the front 02 sensor and clear the codes and see what comes back

This might help with the EVAP code

http://www.obd-codes.com/p0455

Sorry for the double post..

And thanks for the help, I'll start with the plugs, wires, and will move on to the O2 sensor if the first route doesn't fix things.