Ok so I was driving down the road towering a tractor. Then my engine quit. Slow to start back up. Fuel pressure was low so I changed pump. Thenthe CEL came on. P0171 system lean bank 1. So I did research and cleaned throttle body as well as all sensors connected to it. Cleaned both O2 sensors with some crc electric cleaner. Problem fixed for about 30 minutes. CEL comes back on with the same code. A friend of mine said it could be the lack of cats on my truck but this is the first time for this code and I've had my truck for 3years now with my exhaust installed before Igot it. Any suggestions?

 

How old are the 02 sensors ?. If there original with lots of miles on them, then there bad. The 02 sensors need to be replaced every 70,000 - 80,000 miles. Many people over look the 02 sensors, but its just a matter of time before you get a code that pops up.


Other things to check would be the map sensor, it helps control fuel delivery and timing, and the coolant temp sensor.

 

Was it the correct fuel pump? Hows your pressure now.

 

The O2 sensors have I guess 230,000 miles on them. With the truck running if I unplug one at a time you can certainly tell a difference. The fuel pump is correct and I'm getting a constant 49psi even after letting it sit overnight. As far as the map sensor goes if it was out wouldn't it be effecting both banks not just bank1?

 

You only have one O2 sensor that actually monitors fuel mixture ratio. Unless you have a truck with Cali emissions, or, a V-10? Should only be two sensors, on in front of the cat, one behind it. One behind it just measures cat efficiency.

 

Correct, I only have a v8 and nothing in common with Cali. It's there a real way to check the 02 sensor for being faulty?

 

Not really. If you have a scanner, you can see what its doing, but, just because it is doing 'something', doesn't necessarily imply its doing the 'right' thing. If the truck is high mileage, and the sensor is original, replacing it really isn't a bad idea.

 

Is there any other things I could check before I spend $80 on an O2 sensor. In the past week I have spent $500 on this truck trying to fix it and I'm almost at the point off parting it out to get my self another truck.

 

$80? http://www.rockauto.com/ has them for a fraction of that price. Use a discount code and get one even cheaper yet.

 

Unplug the front O2 sensor, and go for a drive. Run better? Replace the sensor. (although, for you, it is WELL past time for replacement in any event.