P0446

[maroman88]

Im at a loss on this one. 1998 Blazer ZR2 with 186k miles, need to repair the cause of code P0446, Evaporative Emission Control System Vent Control Circuit Malfunction. Ive replaced the solenoid and the valve neither helped, but both were all crusted up from age/mileage. I replaced the ECM, now the CEL comes on a lot sooner after a reset. Ive started locating and cleaning grounds. I have no checked the tank pressure sensor, but no codes directly related to that. Short of rewiring the entire emissions system, im out of ideas.

[deadtrend1]

I just had a evap code pop up on my 01. I replaced the 17 year old gas cap with a dry rotted o ring and it seemed to fix it ... :)

[sweetbmxrider]

Check for the following conditions:

- A loose, missing, damaged, or improperly installed fuel cap.

- Missing or damaged O-rings at EVAP canister fuel vapor and purge line fittings.

- A cracked or punctured EVAP canister.

- A damaged or disconnected source vacuum line, EVAP purge line, vent hose or fuel tank vapor line.

- A poor connection at the VCM: Inspect the harness connectors for the following conditions:

- Backed out terminals.

- Improper mating.

- Broken locks.

- Improperly formed or damaged terminals.

- Poor terminal to wire connection.

- A damaged harness: Inspect the wiring harness to the EVAP vent solenoid EVAP purge solenoid and the fuel tank pressure sensor for an intermittent open or short circuit.

A kinked, pinched or plugged vacuum source, EVAP purge, or fuel tank vapor line. Verify that the lines are not restricted.


Testing does incorporate fuel tank pressure sensor in the diagnostic tree.

[maroman88]

I just had a evap code pop up on my 01. I replaced the 17 year old gas cap with a dry rotted o ring and it seemed to fix it ... :)

lmao tried that first.


bmx yea that list narrows it down lol. i assumed when it said Circuit malfunction they meant electrical.

[maroman88]

replaced charcoal canister... fresh air vent hose was packed solid with dried up mud. whoops.

got it to pass inspection once cleaned out.

two days later got CEL for P0442 small evap leak. yea that can wait till next inspection is due :)