I had a new started put into my 2000 Monte Carlo, and now I can't pass my emissions test because the computer won't reset. My mechanic advised me to drive between 55 and 65 mph for 45 minutes to an hour, but I've been driving for 2 weeks and the computer still won't reset. My mechanic also ran diagnostics on it twice, but hasn't found anything. Can anyone help me? I have a court-ordered deadline to get my registration renewed, but can't pass the emissions! Thanks in advance for any info you all can give me -

 

Sorry, we arent ignoring you. I cant post anything long enough to answer you. Be patient, I will keep trying.

 

disconnect the battery, leave car sit for a hour or longer to reset teh computer and force a relearn. then drive to get it to learn the new set up. also might try to put a octane boost in to the car and see if it will help burn some of the stuff out of it

 

From my understanding of how the emissions system works, disconnecting the battery to force a reset is the OPPOSITE of what you want to to. That is the problem in this situation, not the solution. Let me try and post my reply again and see what happens.

 

You know what this is freaking ridiculous. Im starting to get pissed off at the never ending problems this forum is having.

 

From what I understand your problem is that your computer is not giving the "Ready" signal to allow the emission computer to test it. The computer needs a certain amount of time to reset itself. From what I gather, sometimes when you disconnect the battery and then take it right to get emissions done, the computer hasnt gathered the necessary information yet to get the car running 100% and wont give the "ready" signal. I was also told that there are certain shortcuts to getting the computer to give the go. These shortcuts are a combination of actions that a driver performs regularly while driving. Unfortunately, with my limited knowledge I dont know what these are. I would take an afternoon and take a drive through town and intermittently turn on your heat, defrost, a/c, wipers, ect. I would then do the same on the highway. Your computer may also be telling the emissions equipment that there is a problem that will effect the emissions. There could be a problem that is throwing a code, but not turning the CEL on. I would have someone with a scantool take a look and see if there isnt a problem. Good luck. Hope someone else can shed a little light on a solution.

 

PO300
PO403
PO405
PO440
PO446 ✴︎ ⬅︎ ⬅︎ ⬅︎

All these Codes were triggered by a faulty FUEL TANK PRESSURE SENSOR!

Wait for the Low Fuel Warning before attempting to DIY.
Start engine.
Pull FUEL PUMP Relay ... Let Engine stall to relieve pressure in system.
Remove GROUND Wire from Battery.
With car Raised and SAFETY STANDS securely in place.

Support Tank with Jack.

(I made a "Jig" to attach to the Jack. Sawed the square bottom off from Milk Crate. Drilled holes through Hockey Puck. Mounted Puck to center of Milk Crate with Heavy Duty Zip Ties. Affixed carpet to other side of Milk Crate bottom for padding.)

Lower tank enough to access Sensor atop Fuel Pump.
Unfasten Pigtail from Sensor.
Unclip and Remove Sensor ••• Straight-up.
DO NOT BREAK THE END OF SENSOR OFF INSIDE PUMP!!!

If you need a Charcoal Canister do it when you replace Sensor.

Removing Relay to releive Pressure throws a Code which may require a MIL Light reset.

 

My '04 Monte struggled to pass MA DMV Emissions several times.

After re-setting the Codes and turning-off the Engine Light, ... you have to accumulate 80 miles after the reset to be retested.

I managed to do go to the I inspection station a couple times after going to AutoZone, borrowing their OBD2 Reader, resetting the Codes and Light and running-up the needed 80 miles needed on the system to get tested.

Once I was unable to get her 80 miles before the Engine Light came-on, again, ... I rebuilt the whole EVAP System and am very glad I did.

The EVAP Components "Under the Hood" are easily replaced.
1) PCV Valve
2) EGR Valve
3) EVAP System Vent Solenoid

The EVAP Components at the ***-end are a bit of a hassle.
1) Charcoal Canister -- Attached to front on Fuel Tank -- Must lower Fuel Tank.
2) Fuel Tank Pressure Sensor* -- Attached to top of Fuel Pump -- Must detach all Evap Lines and DROP Fuel Tank to have access to remove Sensor from top of Fuel Pump.
3) Fuel Tank Vent Solenoid -- Mounted on removable bracket under Fuel Tank Filler Neck inside Driver Side Rear Quarter Panel -- OEM Tank Vent Solenoid superseded by NEW Model Vent Solenoid requires a Pigtail Jumper that fits NEW Vent Solenoid and plugs into Stock Wiring Harness.