Need Help ASAP

[ajc7755]

Ok sorry for the rush and the double post over in the 94-95 tech page, but I need to fix whats wrong so I can drive my car to a jobsite tommorow. Heres the deal:

Got Check Engine Light
Ran Codes
111 on KOEO - So all good there
172, 136, and 632 on KOER
172 - Heated Exhaust Gas Oxygen (HEGO) sensor - voltage signal indicates lean (Bank #1)
136 - Heated Exhaust Gas Oxygen (HEGO) sensor - voltage signal not switching during Engine Run Self-Test Indicates "lean" (Bank#2)
632 - Overdrive Cancel Switch (OCS) - no switch detected during Engine Run Self-Test

632 probably came up because I forgot to hit the OD button druing the test, so no worries there. But 172 and 136 are a bad O2 sensor right? I kinda guessed this because the CE light only comes on after 5 minutes of driving, which is when the car is warmed up and the O2 sensors are used to check fule mixture.

My question is this : Is this a bad O2 Sensor? And do they codes indicate which side the bad one is on?

Thanks guys, I really appreciate the help.

 

[jrichker]

Both O2 sensors appear to be bad.

O2 indicates system lean. Look for a vacuum leak or failing O2 sensor.

The computer sees a lean mixture signal coming from the O2 sensors and tries to compensate by adding more fuel.

The following is a Quote from Charles O. Probst, Ford fuel Injection & Electronic Engine control:
"When the mixture is lean, the exhaust gas has oxygen, about the same amount as the ambient air. So the sensor will generate less than 400 Millivolts. Remember lean = less voltage.

When the mixture is rich, there's less oxygen in the exhaust than in the ambient air , so voltage is generated between the two sides of the tip. The voltage is greater than 600 millivolts. Remember rich = more voltage.

Here's a tip: the newer the sensor, the more the voltage changes, swinging from as low as 0.1 volt to as much as 0.9 volt. As an oxygen sensor ages, the voltage changes get smaller and slower - the voltage change lags behind the change in exhaust gas oxygen.

Because the oxygen sensor generates its own voltage, never apply voltage and never measure resistance of the sensor circuit. To measure voltage signals, use an analog voltmeter with a high input impedance, at least 10 megohms. Remember, a digital voltmeter will average a changing voltage." End Quote

Measuring the O2 sensor voltage at the computer will give you a good idea of how well they are working. The computer pins are 29 (LH O2 with a dark green/pink wire) and 43 (RH O2 with a dark blue/pink wire). Use the ground next to the computer to ground the voltmeter. The pins and wire colors are for 87-93 cars.

The O2 sensor ground is in the wiring harness for the fuel injection wiring. I grounded mine to one of the intake manifold bolts