Check Engine Codes ...

[carcrazyinga]

I got the Check Engine light and (at the Autozone) I left with 2 different problem codes ... 1). P0171, System too Lean *Bank1* ... i was told this might be the Oxygen Sensor, and 2). P1131, Lack of HO2S switch - Sensor Indicates lean ... now on this one, i was told I'd have to check with a dealer about that one ... would anyone possibly happen to know the cause behind this one ??

[kathy059]

After running my '96 Contour for a year with the check engine light on, I replaced the EGR valve, spark plugs, wires and cleaned the oxygen sensor. The light remained on and still produced the PO171 code. I replaced the mass air flow sensor, reset the car and the light has been OFF for several months now. I also noticed the car running 100% better, lots more get up and go... for a 4 cyl anyway. :-)

[zink88]

Were you able to resolve this problem? What was the solution?

I am getting the same two codes on my 1999 Contour, although the 1131 message indicates "manufacurer fuel air metering".

[Myrosia]

UGH!! I have the same problem...car is stalling and check engine lite is one...Autozone checked and the only code was P1131 !!

Has anyone figured out if it IS the O2 sensor BEFORE the converter...ot should I be checking other things?

SPECS:

I have 66,000 miles

1999 Ford Contour L4-122 2.0L DOHC SFI

Manufacture 10/98

Thanks guys!

Maria

[beyondloadedSE]

all the 02 sensors are before the convertor. P1131 refers to the rear upstream (nearest to the precat on the manifold) bank.

[dxrflyboy]

Originally Posted by carcrazyinga

I got the Check Engine light and (at the Autozone) I left with 2 different problem codes ... 1). P0171, System too Lean *Bank1* ... i was told this might be the Oxygen Sensor, and 2). P1131, Lack of HO2S switch - Sensor Indicates lean ... now on this one, i was told I'd have to check with a dealer about that one ... would anyone possibly happen to know the cause behind this one ??

The two codes are most likely related. If your car is a 4 cylinder, bank 1 is the only bank. In this case your car has two O2 sensors - one upstream of the catalytic converter and one downstream. The downstream sensor is often called a monitor, since its sole purpose is to monitor the performance of the catalytic converter. Although your upstream O2 sensor may be faulty, you may also have another problem causing a lean condition, such as a vacuum leak.