When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
My 91 Bronco 5.0L's check enging light has been coming on and staying on for only a few seconds a few times a trip, so I got out the code reader and read the codes.
On the KOEO test, the continous code I got was:
179 - HEGO (HO2S) sensor fault unable to switch / rich during part throttle
On the KOER test I got:
41 - HEGO (HO2S) sensor voltage low / always lean
Does this mean that my O2 sensor is bad, or could it be something different?
Why is one code saying that I'm running lean, and the other saying rich?
Any ideas?
Double check the codes again. You should have all 3 digit codes or all 2 digit codes, nothing mixed. Check the wiring to the O2 sensor and make sure it has good solid connections. If everything is right there, check for vacuum leaks, and if you find none, it is probably time to replace the O2 sensor.