My 2004 RX indicator lights for Check Engine, VSC and Trac Off lit up a couple wks ago. Took it to dealer and they said it needed a new gas cap. Replaced gas cap and drove away and all was fine about 10 days. Then the lights came on again. Back to dealer and they said for $1000 they could fix it... something about replacing charcoal filter controlling vapors from gas tank that is difficult to reach. Since they said nothing would be damaged by driving it as is, I'm still driving it with these lights on.

I bought an ODB2 scanner and it shows the following two error codes: P0456 and P0442

The scanner (Innova 3130c) can do addtl tests: O2 sensor, EVAP leak, non-continuous test for emission-related powertrain components though the documentation is pretty thin.

Any suggestions for diagnosing this further or repairing it?

 

vent solenoid valve is usually the cause of those codes... its beside the charcoal canister, I wonder if they quoted replacing the entire thing...

 

I do much of my own PM but don't have the service manuals. If I buy the replacement part will it be fairly obvious where/how to replace the vent solenoid valve on my own or are special tools/knowledge required? I've dropped a tank and replaced a fuel pump assembly previously.

 

I took the car to an independent shop that ran a smoke test. They found a rubber hose in the engine compartment that was loose and rubbed a hole ... much less expensive than replacing the vent solenoid valve and/or charcoal canister hidden above the gas tank that the dealer recommended. Replacing the hose fixed the problem and it has not returned in three years.