1999 Escort Trouble Code

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

Any ideas of where to start looking?

Thanks

Jack

Assuming that no work has been done on the engine recently, your problem is most likely at the sensor. If you have had other repairs done recently, don't assume anything.

Check over your wiring for any damage, and if all checks out, you can be fairly confident that a new sensor will clear it up. Make sure you change the correct one (before the cat converter).

If you remove it and find it all gunked up, a cleaning of it may give temporary results. Since it is a '99, it is probably just due to be replaced.