EVAP Control System Monitor (EVAP Leak Check Model)

OBD System Description - EVAP Control System Monitor (EVAP Leak Check Model)

System Description / Monitoring Procedure
ECM boots up EVAP leak check system after 5 hours from ignition switch off and ECM starts EVAP leak check by operating EVAP leak check module (1).
EVAP leak check module consists of EVAP leak check pressure sensor (2), EVAP vent valve (3), EVAP leak detection pump (4) and reference orifice (5).
ECM (17) executes EVAP leak check by the following step.

NOTE: If ECM detects EVAP leak check system malfunction by measuring EVAP leak check pressure (P1 - P4 and P6 - P8), ECM stops EVAP leak check and store it as applicable pending DTC. When starting engine after detecting the same system malfunction two times, ECM turns on MIL.

1. Barometric Pressure Check:
ECM measures barometric pressure (P0) by EVAP leak check pressure sensor while EVAP vent valve is opened (OFF) and EVAP leak detection pump is not operated (OFF).

2. Reference Pressure-1 Check:
ECM measures vacuum as reference pressure-1 (P3) which is generated by EVAP leak detection pump through reference orifice (equivalent of 0.5 mm (0.02 in.) diameter hole) while EVAP vent valve opened (OFF) and EVAP leak detection pump operated (ON).

3. Leak Detecting Pressure Check:
ECM measures vacuum as leak detecting pressure (P5) while EVAP vent valve is closed (ON) with EVAP leak detection pump operated.

4. Reference Pressure-2 Check:
After operating EVAP canister purge valve from close to open then close, ECM measures vacuum as reference pressure-2 (P8) which is generated by EVAP leak detection pump through reference orifice while EVAP vent valve opened (OFF) and EVAP leak detection pump operated (ON).

5. EVAP Leak Check:
ECM compares reference pressure-2 (P8) to leak detecting pressure (P5). If leak detecting pressure (P5) is higher than reference pressure-2 (P8), EVAP system contains a leak which is greater than a leak caused by a 0.5 mm (0.02 in.) diameter orifice.





DTC Description / Detecting Condition / Confirmation Procedure

P0441
Refer to DTC P0441: Evaporative Emission System Incorrect Purge Flow. P0441

P0456
Refer to DTC P0456: Evaporative Emission System Leak Detected (Very Small Leak). P0456

P1420
Refer to DTC P1420: Evaporative Emission System Vent Valve Stuck Open. P1420

P1421
Refer to DTC P1421: Evaporative Emission System Vent Valve Stuck Closed. P1421

P1422
Refer to DTC P1422: Evaporative Emission System Leak Detect Pump Stuck OFF. P1422

P1424
Refer to DTC P1424: Evaporative Emission System Leak Detection Pump Flow High. P1424

P1425
Refer to DTC P1425: EVAP Pump Flow Low. P1425

EVAP Control System Monitor

Operation:

Enable Conditions:

Typical Malfunction Thresholds:

MODE $06 Data

Mode $06 Data: