FJ62 issues with code 21

Joined
Oct 10, 2020
Messages
43
Location
Georgia, USA
I've got an 89 FJ62 and for the past few weeks I've had issues with code 21 :/
At first this happened whilst accelerating (either from a complete stop OR an an engine restart). Eventually that behavior went away - and transitioned to happening every other time I restart the engine immediately after a refuel. I desmogged the engine last week; the cats are gone but the O2 sensors remain; the O2 sensors are aftermarket but they're not malfunctioning. I tested the car all week, driving nearly 200 miles, thru 90+ degree days in metro atlanta traffic; the CEL never went off no matter what I threw (or had thrown) at her. The first and second times I refueled, nothing happened. But the third time the CEL went off. (Like I said, this is the pattern as of late, every other refuel or so). The CEL went away immediately at the next restart.
Naturally I looked through every thread that covers code 21 but none fit this behavior (there was one thread with the code coming on during an acceleration that I want to study a bit since I did experience that initially). Some other info - I replaced the fuel pump and fuel pulsation dampener months ago; the O2 sensors themselves are about 1 year old; I also replaced the ECU after I spotted water damage to it (LONG story there); she's got grounding issues at the rear that appear at random.
So I guess my questions are - has anyone ever experienced this? - aside from the O2 sensor tests in the FSM, what else might I want to do or look out for - and, how likely is this just a random electrical gremlin? I'm inclined to believe a combo of faulty grounding, 30+ year old wiring, and random flukes mimic the conditions that trigger this code.
 
Joined
Oct 10, 2020
Messages
43
Location
Georgia, USA
indeed; once i get my parts together for other fixings, i'm going to inspect the wirings and re-run the FSM tests.

one other question to anyone watching this - there's something about the ECU's behavior that's never been clear to me, does it only light the CEL when it detects a triggering condition? or does it light it occasionally as a reminder that the condition was there?
 

Users who are viewing this thread

Top Bottom