NISMO808

iTrader: (2)

doin a hundred on I95 when the check engine light came on. I figured it had to do with the CAI that I installed this past friday. Pulled the error codes and here's what I got

0903 - EVAP canister vent control valve
0807 - EVAP canister purge control valve/soenoid valve circuit.

I guess first things first, what's a EVAP canister?

Daniel B. Martin

Diagnostic Trouble Code 0903 points to a problem with the EVAP Canister Vent Control Valve. EVAP = EVAPorative emissions control system. This is the system which seeks to minimize air pollution which results from evaporation (as opposed to incomplete combustion) of gasoline.

The EVAP CVCV is located on the EVAP canister (underneath the vehicle near the left rear tire) and is used to seal the canister vent. It has one hose connection and one two-wire electrical connector. The solenoid in the EVAP CVCV responds to signals from the ECM. When the ECM sends an ON signal, the coil in the solenoid valve is energized. A plunger then moves to seal the canister vent. The ability to seal the vent is a necessary part of the diagnosis algorithms for other evaporative loss system components. This solenoid valve is used only for diagnosis, and usually remains open. When the vent is closed, under normal purge conditions, the evaporative loss system is depressurized allowing "EVAP Control System (Small Leak)" diagnosis. Since this part is used only for brief emissions tests the vehicle will usually start and run well despite a Service Engine Soon warning light on the dashboard.

The EVAP CVCV may be bench tested. Remove it from the vehicle (one hose, one connector, two bolts). Verify that air may pass freely through the valve. Then use a pair of fused test leads to apply 12 volts to the terminals to energize the solenoid. Verify that air does not pass freely through the valve. If the CVCV fails these tests, try cleaning it with WD-40 and compressed air. If this fails to free it up, replace the valve. When you install a CVCV (the original or a replacement) always use a new O-ring.

NISMO808

iTrader: (2)

Thanks Daniel. Are there diagrams for locating the canister in the haynes manual?

Daniel B. Martin

No.