My check engine light came on for the first time since i got my 90 4runner the other day. 21 & 43 came up. Is it normal to set these at the same time?
21 is o2 sensor and 43 has me baffled its starter signal.
The light came on after i had been driving it all day and i was on the hiway when it came on.
I did do a compression test with the coil wire off, would that possibly set the 43 code? I hadn't checked the codes before i did the test.

 

try taking your efi fuse out for 10 minz, or disconnect the battery, sometimes it takes the codes away