I have a 88 TP with 22RE, 5spd. The check engine light goes on and off as I'm driving it. Checked the codes and got the 21 & 51, I have recently put a brand new O2 sensor on, so don't understand why I would be getting a O2 code?? Any help resolving these codes would be appreciated....

 

Is your truck running rough? Are there any symptoms of rough idling/poor gas mileage?

Try removing fuse for computer for half hour. That may reset it.

Also, try replacing your TPS or coolant temp sensor (located under thermostat housing with green housing). Two jobs that are not too difficult or costly to do.

 

What brand of O2 sensor? Sometimes the Bosch or others don't tend to work as well as denso or Japan brands.

'89 22RE 4x4 longbed DLX
Sent from my LG-P505 using YotaTech

 

Truck runs normal, don't see any difference in driving it, except the light bugs me

 

What fuse are referrring too??

 

Driver's side fuse box. (Located inside the truck, behind the plastic shroud, next to your left foot.)

Remove the "EFI" and "Engine" fuses for about a half an hour then reinstall them. Should do the trick to reset the CEL.

 

Turns out it is a Bosch that I just recently bought.....Any remedies except for replacing it with another brand?

 

Replace with NTK or DENSO.

 

Code 21 is for the O2 sensor heater circuit, not the sensor itself. I'm not a big adherent to the "Bosch is no good" school, but I don't think it applies to the heater side anyway.

Do pull the EFI fuse for 30 seconds (http://personal.utulsa.edu/~nathan-b...26diagnosi.pdf) to clear up the code 51. Since the code 21 is sensing an open or short in the heater circuit, I'd start with pulling the connector apart and reseating it just in case the connector is open. If that didn't do it, I'd use a multimeter to check for a short/open in that circuit.

You can spend a lot of money on O2 sensors swapping them blindly.