I am having trouble with my check engine light comming on. I went to Auto Zone and they checked the code for me. I was getting a code 133 and a 170. There was something said about the system running to lean. With the 133 code, I replaced both O2 sensors. The light came on again only after about 35 miles and I had it checked again. Same codes with the 2 brand new O2 sensors. The engine runs good, has good acceleration and I do run 93 octane because I do have the superchip. Mileage is 85000 on my truck, with no major problems except that check engine light comming on. I have since reset the computer several times, but the light still comes back on again. Anyone have any suggestions?

Thanks

 

There are 4 O2 sensors. Which ones did you change?

 

The 2 O2 sensors I changed were under the truck, one under the driver side and one under the passenger side. Both fasten into the exhaust after the cat converter. Where are the other two at?

thanks

 

There are 2 (1 on either side) before the cats. They are called upstream O2 sensors. They are inserted right in the exhaust manifolds on either side. They also are the ones that most likely set that code. I don't have my code book in front of me but the code readout will specify which one is being called out as out of range.

 

P0133 is "Upstrean O2 Sensor Slow Response Bank 1." This would be mounted on the exhaust manifold, passenger side. It sounds like is it full of carbon and simply responding slow so it doesn't affect performance too much.

I don't have a reference for P0170.

The O2 sensors on the exhaust manifold usually do fail before the ones after the cats. The only difference between the upstream and downstream sensors is the length of the wire. You may want to simply replace the passenger side upstream sensor with one of the downstream O2 senors you removed and see if the MIL goes away.

 

Thanks alot for the help on my O2 sensors. I found the other 2 just like you all said. Looks like it will be a bit harder to get too than the others. The 2 that I removed were very black and dirty. I don't know if this is common with a truck with 85,000 miles on it or not.......Also about the 170 code, the error said the system was running too lean. Maybe this code is being caused by a bad O2 sensor sending wrong info to the ECM. I'll keep everyone posted and let you know the results of the O2 replacement.



Thanks

 

I had the same problem with my truck, it has 129,000 miles. I replaced the 2 near the exhaust manifolds but the light came back on. I guess the 2 underneath the truck are next.

 

I replaced the other 2 O2 sensors before the cat converter. I have driven 200 miles since, and guess what?....the check engine light has not come back on. I think the problem has been fixed ! (knock on wood). But boy, replacing 4 O2 sensors at $50 a pop ! And the other 2 sensors were sure difficult for me to get to, but I did ! Thanks for all who gave me the info I needed to nfix this problem. Boy, if I had taken it to the dealer, I know I probably paid alot more. The truck is running great !




Thanks