91 Sunbird Check Engine Light - O2 Sensor/Air Temp Sensor?

[bluesmokennoise]

I've had my wife's 91 Sunbird rebuilt considerably by a competent mechanic (which I am not). But this
project has given rise to my "dipping my toes in the water" to learn about automotive things which I am
enjoying as a new hobby. Her Sunbird has developed an anomaly in which occasionally (but not always) as one accelerates above
32 MPH the CHECK ENGINE light illuminates. It stays illuminated until the car reaches 45 MPH, then extinguishes.
I did the ALDL connector jury-rig (paper clip and count flashes) to learn what turned the light on and received a Code 13 (Oxygen Sensor Open) and Code 25 (Air Temp Sensor Out of Range - High). However with the CHECK ENGINE light illuminated the engine
does not run rough or miss.

So I pose my question to this learned group that has already helped me and allowed me to
learn a lot: If this were your car what would you first be checking that might cause these two items to
trigger a CHECK ENGINE light? Does the CHECK ENGINE light's illumination appearance , then
disappearance seem to suggest a transient problem? Unfortunately I cannot to the ALDL check
when it happens because it only happens between 32 and 45 MPH.

Thanks guys.

 

[92 Sunbird LE]

Change the sensors and go from there, O2 sensor should not be a Bosch one, they give false readings...air temp could be a clogged air filter..., But be forwarned....91's are famous for wiring / electrical problems...

Doug in P.R.

 

[bluesmokennoise]

Thanks Doug. You've come to my aid again and I am grateful. I really appreciate your tip about
Bosch. Also flaky wiring doesn't daunt me as I made my living in electronics so I might be slightly
better prepared to find those problems than the mechanical ones
Now if we could just get
some decent weather so I can work on this car. (But they're talking 10 inches of snow tomorrow.
Bet you're glad to be in PR! By the way, the ash tray really looks nice in the car. Thanks again.

 

[92 Sunbird LE]

Your Welcome

The wiring issue is near the fuse box, corroded wires...Also, Check the big plug that goes through the driver's side firewall to the fuse box, mine was loose once due to rusted firewall repair by the previous owner.,

Check also your computer plugs on the computer and wiring through the firewall on the passenger side...( The cowl cold intake gets rusted and leaks some times and rain falls on the computer...).

I have a long list to due on mine , but doing block work currently and waiting on parts..

Doug in P.R.

______________________________

 

[bluesmokennoise]

Doug, those are great suggestions and they're first on my list. In fact I may try to satisfy myself that the
wiring is making contact where it's supposed to and not making contact where it's not supposed to.
Over the years I have solved a lot of problems just by scraping rust, corrosion and mildew off of contacts.
And so often wiring bundles are dressed poorly and stress a wire to break contact or touch ground.
Then I'll replace that O2 sensor and air filter.
Your help is so appreciated.