SES Code Shows Lean Fuel

[Target]

Hello,

I have a 2002 Tahoe with 125,000 miles. The Service Engins Soon light came on and the error code shows, "Fuel too lean Banks 1 & 2." To me this indicates O2 sensors. I changed both, now the light comes on intermittantly. I have looked for the EGR valve, but think I don't have on because I have a flex 5.3L engine, (VIN Z). I have cleared the code twice, but it comes back the same. I have changed plugs and wires as well. I have do have rough idle at start up on cold mornings, but after it is warm, the engine is smooth as glass purring at 500 RPM. Any thoughts on why the light keeps coming on with this "fuel too lean" code?


Thanks,
Target

 

[Sepiroth]

The too lean means that the PCM is commanding all the fuel it can and it still is not enough.

Some basic things to look for are any air leaks from the MAF on to the thottle body, any vacuum leaks under the intake manifold, any exhaust leaks pre O2.

Also you might want to check your fuel pressure and fuel volume. Now I will tell you that having seen this code numerous times, it has 98% of the time turned out being a fuel pump needing replacement.

 

[jniolon]

Hello,

I have a 2002 Tahoe with 125,000 miles. The Service Engins Soon light came on and the error code shows, "Fuel too lean Banks 1 & 2." To me this indicates O2 sensors. I changed both, now the light comes on intermittantly. I have looked for the EGR valve, but think I don't have on because I have a flex 5.3L engine, (VIN Z). I have cleared the code twice, but it comes back the same. I have changed plugs and wires as well. I have do have rough idle at start up on cold mornings, but after it is warm, the engine is smooth as glass purring at 500 RPM. Any thoughts on why the light keeps coming on with this "fuel too lean" code?


Thanks,
Target

let's go a step further and see what my problem is.... 2003 hoe with 160K miles... same codes with the addition of a intermittent "reduced engine power" warning that disappears after letting the car sit for a minute or two and restarting.... occasional rough idle with or without a.c. on... the next time you come to a stop its fine ???? SES light will come and go as it pleases anytime from once a week to staying on for a week...

plugs and wires were changed at 100K... fuel pump replaced around that time also... I'm waiting till next oil change to seafoam the hoe and see what that does for it... although I don't thing it will help this problem...

most times it runs as well as it did the day I bought it... 2 years and 135K ago.

plan on giving it to an independent mechanic shop next friday and see what he can find...

thanks
John

 

[Tahoe7689]

Hello,

I have a 2002 Tahoe with 125,000 miles. The Service Engins Soon light came on and the error code shows, "Fuel too lean Banks 1 & 2." To me this indicates O2 sensors. I changed both, now the light comes on intermittantly. I have looked for the EGR valve, but think I don't have on because I have a flex 5.3L engine, (VIN Z). I have cleared the code twice, but it comes back the same. I have changed plugs and wires as well. I have do have rough idle at start up on cold mornings, but after it is warm, the engine is smooth as glass purring at 500 RPM. Any thoughts on why the light keeps coming on with this "fuel too lean" code?


Thanks,
Target

From what I have heard and experienced, when you get lean bank 1 and 2 it is a MAF sensor. I would say try replacing your MAF sensor.

 

[Virginia Donkey]

I have the cold start rough idle.....then smooth as silk after 2 minutes of driving. Everything I am reading points to intake manifold gaskets.

I have been looking for a procedure online on replacing these, but no luck yet

 

[Sepiroth]

Once you move all the intimidating stuff out of the way and get down to disconnecting harnesses and what not, the removal of the intake is quite simple.

 

[str8wkd1]

I would also say look into the intake gasket common problem

 

[Virginia Donkey]

I replaced my intake gaskets 2 days ago....Man what a difference.

 

[jniolon]

code update

let's go a step further and see what my problem is.... 2003 hoe with 160K miles... same codes with the addition of a intermittent "reduced engine power" warning that disappears after letting the car sit for a minute or two and restarting.... occasional rough idle with or without a.c. on... the next time you come to a stop its fine ???? SES light will come and go as it pleases anytime from once a week to staying on for a week...

plugs and wires were changed at 100K... fuel pump replaced around that time also... I'm waiting till next oil change to seafoam the hoe and see what that does for it... although I don't thing it will help this problem...

most times it runs as well as it did the day I bought it... 2 years and 135K ago.

plan on giving it to an independent mechanic shop next friday and see what he can find...

thanks
John

dropped it off at the shop on way to vacation and told him 'fix it'. Upon return I went by to pick it up with fear of vac leaks, o2 sensors, injectors, fuelpump all being bad...

turns out it was a ground fault... evidently the Snap on code reader found a code that my Walmart special didn't show... 'electrical system fault". They cleaned all the connectors...bulkhead, ignition, etc and removed and cleaned all the ground cables on the engine... evidently there is a TSB on this problem... so far three days and no codes and runs fine...

just a heads up for those with a similar condition... might clean your grounds and see if it helps..

later
John

BTW 40 bucks took it home... way better than the cost of a fuel pump install !!!