Contour Enthusiasts Group Archives Forums General Troubleshooting Help with ODB-II Codes

I have a '97 Contour Sport with a V-tec engine. The check engine light came on, and I got the following ODB-II codes:
P1131 Lack Of HO2S11 Switches - Sensor Indicates Lean
P0171 System Too Lean (Bank 1)
P0133 Oxygen Sensor Circuit Slow Response (bank 1, sensor 1)

Has anyone received these codes, and what did you do to fix them yourself, or is it best to go to a mechanic?

Also, the car has been running a little rough lately.

First Probelm: I've had a few occasions when I'm idle or in park and the engine will rev on its own. For instance I'll park the car then the engine will go from 1000 rpms to 2000 rpms, and it will keep repeating itself. It's as if I'm accelerating, but I'm not.

Second Problem: I'm idle and the rpms will get so low, between 400-500 rpms, and it feels like the car is going to stall. And sometimes it has stalled on me while I'm at a light, a stop sign, or parking. Yesterday was the first time it has stalled on me in a while. The last time it stalled on me was at least 3 months ago, and it was a bit more frequent then.

Any help would be greatly appreciated!

Thanks,
Josie

Sound like a vacuum leak. Check all hoses for breaks/tears and loose connections. You can also check for a vacuum leak by spraying carb cleaner on all of the engine and hose seals. Make sure you spray between the UIM (upper intake manifold) and LIM (lower intake manifold). If there is a leak, the carb cleaner will cause the engine to stumble.

The codes all relate to the same O2 sensor. I'd expect you'll need to replace it. Upstream one on the firewall side. A real PITA to get to compared to all the others. About $65-70 for the Bosch sensor at AutoZone.

It does sound like you have an intermittent vacuum leak. Follow the procedures already posted. You might also have a problem with the IAB valve.

A vacuum leak on the Bank 1 intake would also cause some wierd problems with the O2 sensor as the computer would try to compensate and fail.

Steve

Welcome onboard.

Originally posted by josie:

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I have a '97 Contour Sport with a V-tec engine. ....

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Might be best to properly describe your engine, i.e., I4 (Zetec) or V6 (Duratec) to avoid any confusion in replies.

Hey - you have a Zetec, not a V-tec

http://www.oxygensensors.com/

$50-$56 for the O2 sensors, free shipping. Ordered Thursday, recieved them Saturday.

http://www.oxygensensors.com/