Advanced Diagnostics
Advanced Diagnostics - DTC P0455: Evaporative Emission (EVAP) System Large Leak Detected
General Description
The evaporative emission (EVAP) leak detection system uses a vacuum leak check method and an engine off natural vacuum (EONV) method. This method detects leakage by monitoring the vacuum-retention ability of the EVAP system (from EVAP canister purge valve to fuel tank). The EONV method detects leakage from the change in fuel tank pressure via the fuel tank pressure (FTP) sensor with the engine off.
Here is an overview of the malfunction detection for the EONV method:
Step 0: Judgment of detection of 0.09 inch leak as normal operation [leak check] Step 1: Judgment of detection of 0.02 inch leak as normal operation [phase 1] Step 2: Detection of 0.02 inch leak [phase 2]
Step 0:
Once required conditions for the monitor are met, the powertrain control module (PCM) applies vacuum to the EVAP system line from the purge control solenoid (PCS) valve through the fuel tank, and monitors the variation of the FTP sensor output to detect a "0.09 inch leak".
- If a "0.09 inch leak" is detected, it is identified as a malfunction; the diagnosis is complete.
- If "no 0.09 inch leak" is detected, the PCM goes to step 1, judgment of detection of a 0.02 inch leak as normal operation [phase 1].
- If sufficient vacuum cannot be drawn on the EVAP system line, it is identified as either "EVAP system low purge flow "(P0497)" or "EVAP system leak detected fuel fill cap loose/off (P0457)" (refer to the applicable DTC detail).
Step 1:
After the engine has stopped, the PCM monitors the variation of the FTP sensor output to detect "no 0.02 inch leak" depending on the variation corresponding to the increasing pressure inside the fuel tank.
- If "no 0.02 inch leak" is detected, it is identified as normal; the diagnosis is complete.
- If "no 0.02 inch leak" is not detected, the PCM goes to step 2, detection of a 0.02 inch leak [phase 2].
Step 2:
The PCM continues to monitor the FTP sensor output to detect "no 0.02 inch leak" depending on the variation corresponding to the decreasing pressure inside the fuel tank.
- If a "0.02 inch leak" is detected, it is identified as a malfunction; the diagnosis is complete.
- If "no leakage" is detected, it is identified as normal; the diagnosis is complete.
Monitor Execution, Sequence, Duration, DTC Type, OBD Status
Enable Conditions
Malfunction Threshold
The variation of pressure inside the fuel tank is -2 kPa (-0.6 inHg, -14 mmHg) or more.
Confirmation Procedure with the HDS
Do the EVAP FUNCTION TEST in the INSPECTION MENU with the HDS.
Driving Pattern
1. After the vehicle has been left for an appropriate amount of time as specified, with the engine coolant temperature and intake air temperature within the specified range, start the engine.
2. Warm up the engine at idle until the radiator fan comes on.
3. Drive the vehicle immediately at a speed between 45 - 75 mph (72 - 120 km/h) for at least 20 minutes.
4. After stopping the engine, turn the ignition switch to LOCK (0), and leave the vehicle in this condition for at least 32 minutes (EONV executes).
- Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.
Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected during the first drive cycle with the ECT and IAT at engine start-up within the specified temperature range, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle with the ECT and IAT at engine start-up within the specified temperature range, the MIL comes on and a Confirmed DTC and the freeze data are stored.
Conditions for clearing the DTC
The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the battery.