I recently put a header and a flowmaster muffler with 2.25 in. pipe on my 89 toyota 22re fuel injected motor. My check engine light came on so i checked the codes and came up with the oxygen sensor code #21. Cant figure it out. Has this happened to anyone?
Need help.

 

did you reset the ecu?

 

usually what happens.

 

yes, i reset the ecu and the light came back on a little while later. Is this normal for the light to be on?

 

how old is your 02 sensor

 

It hasn't happened to the last two 22res I've put/ran a header on. I would check the 02 sensor. Just the little bit it moved around when reconnecting the down tube could have damaged it if it's old as dirt.

 

When I tried a pacesetter mine did it. What kind of header you got?

Where is the O2 sensor located could be causing for less than optimal temp range for the sensor.

Not all O2 sensors are the same length, maybe if header O2 bung is deep and you O2 sensor isn't perhaps the exhuast isn't circulating across the sensor.

Made you EGR is FUBR and messing with the O2 readings.

Sufficient backpressure?

Thinks there could be one or two other possibilities, but can remember them.

Dude after thought you sig says '84 22r, maybe the O2 light is coming on cause you ain't got one. Just a thought.

Hope this helps.

 

The light is on my 1989 22re not the 84.
I am running a northwest offroad header. They have the header plus a downpipe to connect to the cat on a stock system. The bung is on the downpipe and is stock for that header. The rest of my exhaust is 2.25in. with a flowmaster muffler.