Contour Enthusiasts Group Archives Forums Modifications Duratec Maintenance O2 sensor codes

The check engine light on my '99 V6 auto
Contour has been on for some time now.
I'm getting two error codes;
P0171-System too lean, bank 1
and
P1131-Lack of upstream heated oxygen sensor switch

The car has 94K miles on it on the original O2 sensors
and I'm tempted to just replace the sensors.
Does anyone know if there is a way to debug an O2 sensor
without an ODBII scanner?
(I know someone is going to ask how I got the codes
without a scanner. I actually got them off my last
inspection. When the inspection station saw the check
engine light they plugged a scanner into the car.
The car passed inspection but the report printed out
the codes.)

A side question, Can anyone recommend an inexpensive
ODBII scanner that works with a laptop PC?

Chenz

Judging by your codes, the one saying bank 1 is lean can be caused by a bad MAF, an intake leak, or simply a bad 02 sensor. Then your second one says that an upstream 02 sensor switch is out or something to the like, so my best guess is that your 02 needs replacing, but go ahead and try everything else first, then see if a shop can check out the 02 sensor for you.

Replace the upstream O2 sensor ( both if V-6).

They're old and tired and are past their time.

www.obd-2.com by Alex Peper

Steve