1998 Honda Civic OBD II Monitors

STEWARTJP

MEMBER
1998 HONDA CIVIC
4 CYL
2WD
MANUAL
130,000 MILES

I have this civic that I am having an awful time with. About 4 years ago a check engine light was on for lean condition. Cleared the code with a generic (Genisis) scanner. Now I cannot inspect my car due to the O2 Sensor, EVAP, Cat Eff. Monitors will not reset. I have tried disconnecting battery, driving through generic OBD drive cycle as well as Honda specific drive cycle, NUMEROUS times. As mentioned this has been YEARS now, the monitors will not reset and I cannot inspect the car, about 15000 miles have been put on it to no avail. Where do I go from here? Alldata mentions pulling a fuse and putting it back in and possibly an idle re-learn, seems kind of evassive to me, ANY other car, drive it enough and right and monitors reset.

4 Replies

BRUCE HUNT

MECHANIC
3,754 POSTS

If the unit does not reset when a scanner tries to clear it, the computer module may be defective.

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Tuesday, December 16th, 2008 AT 4:09 PM

STEWARTJP

MEMBER
3 POSTS

No the scanner WILL clear out the computer and set all monitors to "not ready" the issue is that after driving it all monitors will set to "ready" except for the o2, EVAP and cat, which for OBDII emmissions testing means you cannot pass. I have however found someone who has had the same issue and replacing the ECU has fixed the problem. So I will try this, hopefully I can get away without reflashing but I know the serial numbers on the other computers, security for instance, will not match and probly cause even more issues. Thanks for your help though

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Tuesday, December 16th, 2008 AT 5:27 PM

RYANBLIZZ

MEMBER
35 POSTS

Check the "Backup Radio Fuse" in the fuse box under the hood. The auxiliary radio circuit (to store your presets) also is the auxiliary power for your ECU that saves your sensor information. I helped a friend with a 1998 Civic EX try and pass inspection for two months before he found this out.

He would drive it, hook it up to a scanner and all sensors would read "Ready", then shut it off and turn it back on and the O2, EVAP and CAT sensor would read "Not Ready". He replaced the dead fuse and now all sensors read "Ready" and it passed on the first try.

Good luck!

Ryan

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+2

Thursday, February 5th, 2009 AT 5:56 PM

RYEISENMAN

MEMBER
1 POST

Thanks ! That's what was happening on my 1999 Honda Civic (and sure enough the Backup Radio fuse was blown). The C EV O and OH would show not ready / not run / not completed whenever I started the car. I'd drive the car for half an hour and check with an OBD reader and the C O and OH would be OK. But then turn car off and turn the ignition back on and the OBD computer would forget that it had run them and would show not ready again. And the EV / EVAP would never run. Hopefully the EV will run after sitting overnight (somewhere else someone indicated that EVAP won't run unless the car sits for awhile, and the computer would need to remember that it had been sitting for awhile).

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Friday, June 6th, 2014 AT 5:11 PM