View Full Version : Check engine light on, CODE 41, Oxygen sensor reports lean condition, what now?

08-22-2002, 05:57 PM
I got this during the Key on Engine Running and the Key on Engine Off (continuous memory) test. The check engine light will come on and stay on for a good while, then go off, then spradically come on and stay on again. Also, when I give the car full throttle (89 Tbird SC 5speed), once she hits full throttle, she seems to fall on her face, like someone took away the boost. She idles fine, no bucking or stalling, just that damn code. Does that mean the Oxygen sensors are shot? thanks

Phil Stocker

08-22-2002, 08:47 PM
Suggest you check fuel pressure first, I think it should be around 40psi. But the code 41 (in memory) indicates the right heated O2 sensor. (91 is left) It could be caused by vacuum leak or even plugs/wires/coil/dis. (Your discription of how it idles fine and falls flat on top end makes me think fuel flow, but what makes sense to me doesn't always mean much.)
If all checks OK, you should be able to get a meter on the wires to the sensor. When warm they should be switching from below 4.5VDC to above it. (If not sure what your are reading, compare to the left side.) If low, pop the air filter and flow in some propane, you should see the increase. Again if all else looks good, it should be the right sensor.

Goodluck & let us know

08-22-2002, 08:49 PM
Correction on voltage: above & below .45VDC not 4.5