bronxfox

2003 Grand Cherokee 2wd 4.0L
All codes are cleared. Drive 75-100 miles and the check engine light comes on.
I've replaced all the O2 sensors, replaced the wiring harness, brand new battery, fixed a short at the fuse box under the hood at the fuel injector fuse.

The only message I get is that the oxygen monitor is being triggered. But when the car is put on the computer all the emissions are within normal.

Can someone please clue me in on how to get this fixed so I can pass smog and get the check engine light to stay off..which frankly its been more on than off for 11 years!

johnny james

I would just clear the code before you get the smog test, best to drive it some before the test so its at norm temp. Their not going to drive it so they can't set it off. You must have something else going on cause my answer to
your question seems to easy. This is assuming you have a scanner to clear the code.

bronxfox

All codes are clear. Then I drive it for 80-100 miles and either the smog shop tells me its not ready to be tested because of the evap and the oxygen monitor circuit or the check engine light comes back on for the oxygen monitor circuit..Yet all the emmissions and voltages are within code when put back on the computer..

outofrng623

Whats the actual P code you are getting?

johnny james

Can't help you with mechanical stuff you'll have to go to a mechanic for that, although you might do a smoke test on the evap problem to see if there's a leak somewhere, that's my problem right now. You are not saying what the code is? This might help you with the drive cycle setup.

outofrng623

Was this ever resolved? If so...What pcode and what did you do to fix? THANKS!

johnny james

2 evap hoses, pcv hose and the valve , the other was on the box that's located below the air filter. You need to take off the grille and the front
bumper to get at it.

You need to do a smoke test, makes it easier to find the leaks, it threw three codes , small leak/big leak and one that said it was the purge solenoid which was a false error code, I don't remember the code numbers

If you google "drive cycle" it will show you how to perform all the monitor
checks, if you follow the instructions it only take 15 mins.

johnny james

Sorry that was my Tacoma that had the 430 code, it was a exhaust pipe leak before the cats and sensors. I don't think it matters what vehicle the 430 code is on though.

outofrng623

Thanks. Was so hoping it was something simpler. Lol
I'm getting the 420, but the cats new and so are the o2s. The failing sides o2 looks somewhat fouled...
I have the power train service manual which has the test conditions...I know how to get it to throw the code, just can't figure out why. Lol

Thanks!!

johnny james

Ok , I'm not good with numbers it was a 420 not a 430 code, the exhaust leak screwed up what the sensors read.

outofrng623

Curious on your evap issue...were your rpms high?
420 430 same difference just opp side of the motor.

bronxfox

So.. mechanic did a smoke on the evap system and found a crack in the hose near the rear differential. cut off an inch or so and that code was cleared. I passed smog, but only cause the technician passed me thru. The oxygen monitor would never get passed the ready stage and eventually at 185 miles the check engine light came back on.

All my monitors, etc are reading within limits for smog, but no one can tell me why the check engine light keeps coming back

I've replaced: all oxygen sensors, the wiring harness, oil pressure sensor, battery, radiator, temperature sensor in radiator, hoses. In 9/2013 the transmission was replaced as well.

Car drives great, gas mileage is better than ever, 135,000 miles. But the check engine light issue seems un-fixable.

Wondering if the computer/cpm needs a replace..

outofrng623

Bronxfox...Bronx ny? Yonkers here. What's the actual code you're getting?