markf1

My 1989 4x4 Pickup with 22re engine, 170K miles, is getting an intermittent check engine light. Seems to come on after driving for maybe 10 minutes uphill. Goes off after a while if driving on level or back downhill. Last year replaced timing chain, mass airflow meter and tps. No problems with performance or anything up until just recently.

I followed the instructions from a thread here and also some similar youtube videos. I have the small diagnostic connector on passenger side of engine. I jumper across the T1 and E1 connector/terminals. When I turn the key to the start/acc position I get a solid check engine light. No blinking to indicate diagnostic code. It seems like a pretty straight forward process but it does not seem to wok for me. Any ideas of what I may be doing wrong with trying to check the diagnostic codes or....? Thanks!

Co_94_PU

iTrader: (-1)

Post a photo of your diagnostics port with your jumper in place please. I suspect your in the wrong positions.

markf1

Thanks for your reply! Do I feel stupid. Just by taking the photo I realized, yes I was jumping across the wrong connectors. Couldn't be more clear but I was having a repetitive brain cramp. probably cause I'm turning 60 soon. drain bamage.
So I'm getting code 25 and code 26 next step is to find what those mean. Thnaks again!

se7enine

iTrader: (2)

25/26 are lean/rich air fuel ratio. I would start by checking the O2 sensors.

markf1

OK and Thanks for that. I got a list of what the codes indicate below:

25
AIR/FUEL RATIO LEAN INDICATOR--LEAN SIGNAL SENT TO ECU FROM O2 SENSOR
--INJECTOR FAULT(S)
-FUEL PRESSURE
--OXYGEN SENSOR
--AIRFLOW METER OR MAP SENSOR
--IGNITION
--ECU

26
AIR/FUEL RATIO RICH INDICATOR
--SAME AS ABOVE
--COLD START INJECTOR

I am searching for info on how to test the O2 sensor. I have found some people stating that it should be replaced after 100K miles regardless. I believe mine is still the original. I'm the only owner and it has 170K miles so maybe I should just order one and put it in? Looks pretty simple to do - two bolts. I'm not a pro mechanic but i'm reasonably handy and have tools, metric sockets etc. Like to do what i can to save $.

se7enine

iTrader: (2)

If you do replace get the denso or NGK brand. About $53 from AutoZone. X2 if you have more than 1.

markf1

se7enone, Thank you so much for your helpful replies! I have read about using the Denso brand as preferable and that”s my plan. I have got some confusion regarding wether I have 1 or 2 on the truck. I’m not on CA. I’m in CO and the truck came new from dealer inWY.

I’m going to look in the morning to see. There should be one just under the exhaust manifold inthe engine compartment and maybe another just past the Cat on the exhaust system. If I understand correctly.

I entered my make model erc into a order order on amazon and it returns the same sensor for either location, I think. Sort of confusing.