Q&A

 Journeyman

The car is 13 years old, the canister is plastic.There's some info.

Vehicle Application: 1998 Toyota Camry 2.2L, Vin G, Eng Cfg L4, Eng Des 5SFE

Customer Concern: Check engine light is on with a code P0446. On the early evaporative systems, this code is for a leak in the charcoal canister.
Tests/Procedures: 1. Verify that the 3-way Vacuum Switching Valve (VSV) on the canister operates correctly. When the VSV is not grounded, the Fuel Tank Pressure (FTP) sensor should be connected to the canister side of the system only. When the VSV is grounded, then the FTP sensor should monitor only the fuel tank.

2. Monitor the FTP sensor, unplug the 3-way VSV, draw a vacuum into the canister and verify that it will hold vacuum and the pressure sensor voltage will decrease.

3. Test and verify that the purge solenoid and wire harness are all OK. The purge solenoid should apply vacuum to the charcoal canister when grounded. Also verify that the hose from the purge solenoid to the charcoal canister does not leak.

4. On a 1998 Camry, we have seen a few problems with the connector under the backseat cushion. The connector has the wires for the pressure sensor and the VSV under the vehicle.
Potential Causes: Charcoal Canister
Leaking Evaporative Hose

Tech Tips: It is common for the 3-way VSV to stick or not operate correctly or for the charcoal canister to be faulty. The charcoal canister has many check valves and springs built inside, so always replace the canister and 3-way VSV as an assembly so the code does not reset.
Diagnostic Codes: P0446

 Master

We see lots of problems with the canisters and valves,Toyota used to sell the valves mounted on the canister separately but replacing the canister and valves complete assembly cures the problem if the codes stored pertain to the canister and valves. The hose up at the air filter gets knocked off during air filter replacement but I am sure that got checked, the two electric solenoid valves in the engine compartment also fail intermittently but again I am sure that was checked. Canister replacement is quite simple Under the car at rear above rear sub frame.

 Journeyman

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