1995 Dodge Stratus • 4 cylinder Automatic • 200,000 miles

The car has started giving a "Code 51". Oxygen Sensor signal input indicates lean fuel/air ratio conditioned during engine operation.

Any help on what might be causing this or what I could check to correct it would be greatly appreciated.

Thanks so much!
March 29, 2012.

How is the car running? I would first test the o2 sensor. Monitor the signal wire with a lab scope or scanner add fuel check and see of your voltage rises up to 900 mv then give it a large vacuum leak to see if it drops close to 0 mv. This will tell us if the o2 is working and can be trusted.

Mar 29, 2012.