SES Light - 3 codes - P0102, P0443, P0449

06-17-2007, 04:18 PM
Any ideas what could be wrong?

The SES light came on while I was at an ORV park, after off-roading for about 3 hours.

P0102 - Mass Air Flow Sensor Circuit Low Frequency
P0443 - Evaporative Emission Control System Purge Control Valve Circuit
P0449 - EVAP Canister Vent Solenoid Valve Control Circuit

I checked the vacuum lines under the hood and it appears I have no leaks, I'm going to hook a vacuum gauge up in a minute and see where the vacuum is at idle.

MAF is plugged in, gas cap was removed and re-tightened, I cleared the codes when I read them and they came back after a short drive.

truck is a 2001 4x4 blazer LT, with 106k miles. I replaced the starter 3 weeks ago, put about 800 miles on it since then.

edit: just drove to blockbuster and back, and checked the vacuum (so it would be fully warmed up)

18" at idle, check at the vacuum distro by the drivers side firewall.

so I don't think there's any vacuum leaks.

one other thing I forgot to mention is I replaced the fuel filter when I replaced the starter.

06-18-2007, 05:17 AM
Lots of hard bumping - make sure the MAF is clean (spray it off with MAF, electroic or brake but not carb cleaner) and make sue the gas cap is tight and the rear evap unit rear drivers side is not damaged (by off road hits.
Then reset the light and see if OK - in fact just resetting the light and none will return. The vent solenoid is located pass side under hood on rear of engine along the valve cover and intake all the way back.

06-30-2007, 10:45 PM
I pulled the intake apart and cleaned the MAF out with QD electronic cleaner, cleaned the IAC valve, pull the throttle body off and did the little cutting off the restrictor plate deal mod, cleaned everything off with QD electronic cleaner, jacked up the rear and checked out the evap canister by the back bumper, all connections and lines were solidly plugged in and there were no cracks leading to the gas tank, I checked the valve on the valvecover and it similarly was fine, I pulled the connector off and sprayed it out with the QD stuff also...

cleared the codes, went for a quick drive to the bank and back, and the SES light was back on when I restarted the truck at the bank. Came home, read the codes and cleared them again, and it was the same 3 codes...102, 443, 449...

when I was cleaning off the MAF, I noticed on the connector for it that 2 of the 3 wires had exposed wire as if it had rubbed something and worn through, so I took the wires out of the loom and tinned them, then individually wrapped each wire with a generous amount of electrical tape then routed them back into the loom and wrapped the end with tape, I was hoping that would at least fix the 102 code but it didn't...maybe I need to replace the plug?

I think I'm just going to replace both of those valves/sensors that have circuit malfunctions and hope for the best.

gas mileage seems to have taken a hit, but I assume the computer is in limp mode right now, I'm just slightly above 1/2 tank and I've only gone 107 miles on that 1/2 tank...mostly freeway!

06-30-2007, 11:41 PM
I was just about to order those valves, but I just can't wrap my head around both failing like that.

I think they are connected by the same vacuum line, right? Is there anywhere I can get a vacuum line schematic showing how that line is routed on the truck so I can trace it? The one on the valve cover looks to drop around behind the distributor and back towards the gas tank/evap can, is it connected directly to that other valve?

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