My SES started flashing at me the other day, and it has been doing so intermittently for the last couple of days. Only flashes while the motor is warming up in the mornings, and runs the same as always. Throwing two P0440s, a P0300, and a P0449. The P0440s and the P0300 have been there for a few (working on trying to get rid of the P0300) but the day the SES started flashing I pulled the codes and the P0449 is what popped up new. Any ideas? And, while talking about the P0449: Called the dealer to get the part and they said there is a new "jump harness" that I have to buy. None of the previous threads have mentioned this. Anyone else dealt with that?

I love my girl, but I'm about to kick her... Not to the curb, just kick her.

 

An ignition voltage is supplied directly to the evaporative emission (EVAP) canister vent valve. The control module controls the EVAP vent valve by grounding the control circuit via an internal switch called a driver. The primary function of the driver is to supply the ground for the controlled component. The control module monitors the status of the driver. If the control module detects an incorrect voltage for the commanded state of the driver, DTC P0449 sets.

I would check the connector at the vent valve first. The dealer might be correct about the jumper harness as the replacement valve is relocated outside the frame rail. Hope this helps.

 

I had to read it twice to wrap my little mind around it but yes. And thank you. I'll update after I replace the EVAP vent valve

 

fix the misfire pronto before you damage the catalytic convertors. a flashing mil is an indication of a misfire and pending cat destruction if you keep driving it. The cats will overheat and meltdown from raw fuel entering the cats. the evap stuff can wait as it won't damage anything.

you need to isolate the misfire to the offending cylinder. a full function scan tool can record misfire counts for each cylinder.

 

I agree with tech2. EVAP can wait. Converters can go from 700*c to the start of melting point of 1200*c in a manner of seconds, when raw fuel combined with air from the misfire are introduced.

 

When I first got the pO300 I had a mechanic run a full scan on it. There are actually three different cylinders misfiring, 3, 5, and 7 (or maybe it was 8? - I'll have to look at the notes from the mechanic.) Anyway, we put in new ACDelco plugs, and we are planning on doing the o2 sensor next as it's the only thing he found on the diagnostic that could/would cause a misfire. I've been holding off since hubby's POS Prelude needs a transmission but frankly I care more about my girl than his car anyway.

 

if the misfires are all on one bank 1,3,5,7, a bad 02 or clogged catalytic convertor may be the issue.

To check for a clogged cat; remove the bank 1 sensor 1 (pre cat) 02 from the y-pipe and test drive to see if the misfire is gone. the open exhaust will bypass the restriction in the exhaust stream.

 

tech2 I found the paperwork from the mechanic and he recommended B1S1 and B2S2 both to replace. I will go ahead and replace B1S1 since I already bought it and I'll go from there. If I still have the misfire I'll move down the line. I'll update after this weekend when we swap them out. Thank you!

 

Update: Replaced B1S1 O2 and (drumroll) NO MISFIRE! I also have lost both P0440 codes as well so that was handy. Still have P0449 so I'll try to get the vent solenoid replaced this coming weekend. Hell, at this rate I might be able to pass emissions on the first try. How handy.

 

great to hear.

the p0440 monitor won't run until the misfire was fixed. It still hasn't run yet. the 02 won't fix it, but the vent solenoid probably will take care of both p0440 and p0449