Thread: Car randomally runs like a** on >1/2 tank

Also have a check engine light on now...has 2 codes in the computer

po300 for a Random Multiple Cylinder Misfire

and

po420 for Catalyst System Efficiency Below Threshold (Bank 1)

and last week while driving around when the car was acting up, it gave me code

po131 - Oxygen O2 Sensor Circuit Low Voltage (Bank 1, Sensor 1)

So it seems like whatever it's doing either has to do with the O2 sensors or it's effecting them in some way. And I just replaced the catalytic converter so what are the odds it's already bad?

Originally Posted by 99gtxws6

Also have a check engine light on now...has 2 codes in the computer

po300 for a Random Multiple Cylinder Misfire

and

po420 for Catalyst System Efficiency Below Threshold (Bank 1)

and last week while driving around when the car was acting up, it gave me code

po131 - Oxygen O2 Sensor Circuit Low Voltage (Bank 1, Sensor 1)

So it seems like whatever it's doing either has to do with the O2 sensors or it's effecting them in some way. And I just replaced the catalytic converter so what are the odds it's already bad?

going out on a long shot here...but here it is.

i think your fuel pumps the problem. the 02 sensor low voltage means that your leaning out, which can also cause the random misfire and the catalyst below efficiency code. like i said im going on a long shot, but i do know that low voltage on an 02 sensor like say 200mv is lean and say 900mv is rich. maybe someone else can help you more.

Originally Posted by kfish

going out on a long shot here...but here it is.

i think your fuel pumps the problem. the 02 sensor low voltage means that your leaning out, which can also cause the random misfire and the catalyst below efficiency code. like i said im going on a long shot, but i do know that low voltage on an 02 sensor like say 200mv is lean and say 900mv is rich. maybe someone else can help you more.

I guess I'm going to go ahead and put this new fuel pump in. It's starting to have problems now no matter how much gas I've got in it. But it only does it after I've been in traffic a while and it's hot outside still. Kinda weird.

Like, for about a mile til I get to work, there's construction and traffic backs up, so I'm constantly stopping and accelerating and once I do that for a few minutes, the car starts acting like it's running out of gas. Sometimes it'll die but I can always cycle the pump 3 or 4 times and it'll start again.

Well Friday it died and I'd turn the key back and forth probably 10 times and the pump would never cycle on. Just let it sit for about 5 mins on the side of the road, tried it again, and the pump cycled back on, car started back up, and I drove the rest of the way to work.

So hopefully the new fuel pump will do the trick, just hate having to cut and splice the different plug into the stock harness.

Swapped the fuel pumps and the problem has seemed to have gone away. I've run it under a 1/4 tank many times while in traffic and hitting stop lights and it's not had a problem yet.