The evaporative emissions system prevents hydrocarbon (HC) vapors from the fuel tank from escaping into the atmosphere where they could form photochemical smog. Gasoline vapors are collected in the charcoal canister. The Canister Closing Valve (CCV) closes off the air inlet into the canister for leak detection of the evaporative emission system. The CCV also prevents fuel vapors from escaping from the canister. When the engine purges the HC vapors from the canister, the clean air comes into the canister through the canister air-filter and the CCV.
The PCM measures pressure in the fuel tank by means of tank pressure sensor during all engine operating states except engine stop and start. PCM sets DTC P0449 if the PCM detects that the fuel tank pressure is too low as a result of the stuck closed CCV.
Item | Detecting Condition | Possible Cause |
DTC Strategy |
•
Ventilation control valve stuck closed | 1. Canister air filter contamination 2. Faulty CCV |
Enable Conditions |
•
Leak detection test not active
•
No tank pressure sensor error
•
11V < Battery voltage < 16V | |
Threshold Value |
•
Fuel Tank underpressure(below - 30 hPa) too high
•
Differential fuel tank pressure V_DTP < 1.6V | |
Diagnostic Time |
•
10 Seconds | |
Mil On Condition |
•
2 Drive Cycles |
Canister Close Valve | Normal Parameter At 20℃ (68℉) |
Resistance | 23 ~ 26Ω |
