Contour Enthusiasts Group Archives Forums General Troubleshooting Check engine light on Ran codes...

Check engine light has been on for a while in my 99 SE with 68k miles. I was at autozone today and decided to have them run the codes. I came up with the following

P1131 Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 1.

P0171 System Too Lean - Bank No. 1.

Car doesn't seem to have real bad performance although gas mileage is good, it's not as good as it used to be. Anybody have any idea what this is and how simple of a fix it is?

Might be the upper O2 sensor on the rear bank. (If this is a V6) This is hard to reach, but is not bad if you remove the coil back, climb on top of the engine, and use a long skinny breaker bar with a sensor socket. Others have used a stubby wrench, pipe and hammer to loosen the sensor. Try a search for O2 sensor and you should find lots of advice.