I have a '96 Civic HX 1.6L Vtec-E, 200K miles, manual trans, only mod is intake filter and tube. No codes present/stored. Just 2 un-run monitors in the ECU-- 1. Catalyst monitor, and 2. O2 sensor monitor. It also has an EGR system monitor that is un-run, but the car doesn't even have EGR, so that's it's own thing. The O2 heater monitor runs and passes after a short time of running(3 mins?). I tried a new used ECU, same exact thing. I'm *guessing* it could be O2 sensor related. This car uses a FIVE WIRE O2 as the pre-cat, and a 4-wire for the post-cat sensor. The first sensor reads .5V unless you rev it up--then from .35-.65ish for a second. The second sensor reads .8 unless revved, then .00-.80V. My next step is to replace the second O2(it's not $400 like the first one). Any info would be appreciated. I've been doing searches and reading over an hour with no good info on HX engine management. PLEASE HELP!

 

how long has it been since your ecu was last reset? it can take weeks for all the readiness tests to clear. are you just trying to pass inspection? in NY you can still have 2 tests that haven't cleared, and pass inspection.

 

It had been months. No codes are stored, just 3 un-run monitors. The EGR I hear is commonly un-run, my guess is because it doesn't have EGR..stupid car, but the O2 monitors should be run and the results stored in memory. I'll be installing a post-cat O2 in a day or so here and see if anything changes.

 

 

YEP, Missouri Emissions, which are second to California in terms of strictness.

 

gotcha


I really don't know what it could be, tell us what happens after your install...