I need help from a GM tech

[jryerson]

Ok, here is the history. I have a 96 chevy silverado with a 5.7l engine. About 8 months ago i began getting an SES light. codes were 275, 272, and 420,430. at that time I thought the o2 sensors were going since they had never been replaced. I replaced all the o2 sensors, replaced the cats ( need to be replaced anyway), cleaned the throttle body, egr valve and ran some seafoam through it. Just recently I replaced the fuel pump because it wasn't providing enough pressure. I still have the 275 code. I believe it is a "rich condition bank two". If there are any GM techs out there that might be able to help me with this I would appreciate it. By the way the engine has 145000 miles runs like a watch and has never missed any maintenance.

[ridnlow]

Might be stupid.. but have you tried some different gas? I want to say i got this code on my old tahoe.. had it cleared used some 93 chevron gas and it never came back...

[jryerson]

I have used different gasses and different grades. I did notice it occurring less with higher grade gasses. However, I haven't used any premium gas due to the high gas prices.

 

I was wondering if maybe an injector could be going bad in bank 2 since this is the code i'm getting.

[DEV1ST8R]

When it comes to gas, you get what you pay for! Especially when comparing cheap and unbranded gas. . .with say, Chevron. Just like with people, the "healthier" the stuff you put in it, the better and longer it'll live.

[GMCTech]

It's tough to diagnose a problem like this without hands-on.

 

You'll need to find someone that knows how to read O2 sensor data on a scan tool. You'll bea able to see if there is extra fuel being dumped in by a stuck open injector.

 

A bad fuel pressure regulator can also be the culprit.

 

Hope this gets you going in the right direction.