Dtc P1131

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Jan 31, 2005 | 10:52 AM

mwaller

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Dtc P1131

The MIL check engine light is on on my 1999 Expedition (111,000 miles), and the DTC code is P1131 (P1131 is HO2 Sensor not switching -- Too Lean). Before assuming it is my O2 sensor, should I run any other diagnostics or just assume it is the sensor? Any help would be appreciated. Thanks!

Mar 20, 2006 | 08:47 PM

davez41

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I also have this problem

99 expy 5.4 with MIL on, p1131 code, truck seems to run fine?

Mar 20, 2006 | 09:44 PM

FTE Herman

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I don't think that it's an 'assumption'. Replace the sensor.

Mar 20, 2006 | 10:06 PM

davez41

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I have the sensor in front of me, Bosch 15716

Is it an easy Job? Should I buy the special socket? Go from underneath the truck or through the fender well? I was deterred by the electrical connection location, tucked way up behind the exhaust manifold. Can I pull on it to give me more slack? Any help greatly appreciated!
Thanks
Dave

Last edited by davez41; Mar 20, 2006 at 10:24 PM.

Mar 21, 2006 | 08:32 AM

mwaller

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I did it last year without any special sockets/tools etc. It took about 1 hour and wasn't too bad... The electrical connection was tight but just loose enough to get it out and the exhaust manifold was in the way but workable. No problems since. Good Luck.

Mar 21, 2006 | 09:14 AM

coldairintake

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The socket is worth every bit of the $5 or $10. If you can get the vehicle on ramps, the job will be a lot easier. You might have to feel around for the connection release. Just look at the new sensor and the release will be the same. Be careful not to burn yourself on the manifold. Sometimes the engine needs to be warm to remove the sensors since the metal contracts when it's cold. Let us know how it comes out.

Mar 21, 2006 | 09:06 PM

davez41

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O2 Sensor removal scheduled for this weekend.

Thank you guys for all your experience. I am going to replace the sensor this weekend. I will keep you posted on my progress.

Dave Z.

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Mar 24, 2006 | 08:50 PM

davez41

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Code P1131

Hi again everyone. I have a 99 XLT expy 4x4 that had a mil light code of P1131 show up on the truck about 6 months ago. I narrowed this down to the passenger side, upstream (pre-cat), oxygen sensor. The hardest part about replacing this sensor is the electrical connection. I turned the wheels to the far left so I could fit my body in behind the wheel well as I looked up for a better view of what had to be done. However, most of the job was done by "feel" from underneath the truck, as I could not see much! I found out that by breaking the sensor loose from the exhaust pipe and then unscrewing it from the pipe, (without tangling the wires around the sensor), then, letting it hang down so I could grab it with my left hand while my right hand unclipped the electrical connector, was the way to go! It took about an hour. Just a 22mm wrench on the sensor with a "jimmy wrench" for more leverage on the 22mm wrench and she came free.

Hooked up a obd2 scan tool, cleared the code, and the mil light has not come on in the last 5 trips to town. Thanks to this forum, life is good!
Dave Z.