P0442
DTC P0442 EVAPORATIVE EMISSION CONTROL SYSTEM LEAK DETECTED (SMALL LEAK)1. OUTLINE OF DIAGNOSIS
The evaporative system monitor detects leak up to 0.020 inch in the fuel tank and evaporative emissions system. If the fuel cap is not present or has not been correctly tightened after a refueling event, a malfunction is also detected. These malfunctions are detected by monitoring the fuel tank and system pressure during an intrusive pull-down pressure test. Pull down is accomplished via the purge valve while the engine is running. Monitors run during the first idle after engine start and while driving.
The diagnostic is classified into two monitors. The first monitor detects a 0.040 inch leak, fuel cap loose/off, and canister purge valve stuck open/close whilst the other monitor detects a 0.020 inch leak when the vehicle is moving or during the first idle. Failures, DTCs and monitor methods are as follows.
Monitor 1
- P0457 Fuel cap loose/off or CPC valve stuck open/close
- P0442 0.040 inch leak check
This monitor detects CPC valve stuck open/close, fuel cap loose/off, and 0.040 inch leak in the evaporative emission system by monitoring the fuel tank system pressure an intrusive pull-down pressure test. The monitor consists of Modes Z, A, B, C and D. There are three judgment times for these malfunctions. CPC valve stuck open is performed in Mode Z, CPC valve stuck closed or fuel cap loose/off is in Mode B, 0.040 inch leak is in Mode D.
Monitor 2
P0456 0.020 inch leak check
This monitor detects a very small leak (0.020 inch) in the evaporative emissions system by monitoring the fuel tank and system pressure during an intrusive pull-down pressure test. Pull down is accomplished via the purge valve while the engine is running. The monitor runs during the first idle after engine start and also while the vehicle is running.
2. ENABLE CONDITION
3. GENERAL DRIVING CYCLE
Monitor 1
Perform the diagnosis when the cumulative time of canister purge after engine start becomes 120 seconds or more, at a vehicle speed of 32 km/h (20 MPH) or more.
If judgment cannot be made, repeat the diagnosis after a predetermined interval has passed.
Monitor 2 (first idle condition)
Perform the diagnosis only once at the fast idle (the idling before starting to move) after soaking of 5 hours or more, in conditions that A/F feedback has been executed and catalytic converter has been warmed up (approx. 25 seconds after engine start).
If judgment cannot be made, or the diagnosis cannot be performed at fast idle, do not repeat the diagnosis in this driving cycle.
Monitor 2 (vehicle running condition)
Perform this procedure only when the diagnosis cannot be completed at fast idle.
Perform the diagnosis when the cumulative time of canister purge after engine start becomes 120 seconds or more, at a vehicle speed of 30 km/h (18.6 MPH) or more.
If judgment cannot be made, repeat the diagnosis after a predetermined interval has passed.
4. DIAGNOSTIC METHOD
- Monitor 1
- CPC valve stuck open
At the beginning of the Monitor 1, system performs CPC valve stuck open monitor in Mode Z. CPC valve and CCV are closed and the fuel tank pressure is monitored. The pressure transition over a calibrated time is then used to determine if the CPC valve is stuck open.
Judgment
- Pressure difference in Mode Z less than 0.9 kPa (6.5 mmHg, 0.3 inHg) --> Fail [CPC valve stuck open]: P0457
- Pressure difference in Mode Z ≥ 0.4 kPa (3 mmHg, 0.1 inHg) --> Pass --> move to Mode A
- Fuel cap loose/off and CPC valve stuck close
Fuel cap loose/off and CPC valve stuck close monitor is performed in Mode B of Monitor 1. The engine lowers the fuel tank pressure using intake manifold vacuum via the operation of the CPC valve. The pressure transition over a calibrated time is then used to determine if the Fuel cap loose/off or CPC valve stuck closed.
Judgment
- Elapsed time in Mode B ≥ 10000 ms and (Minimum tank pressure in Mode B) - (Initial tank pressure in Mode B) > -0.5 kPa (-4 mmHg, -0.2 inHg) --> Fail [Fuel cap off or CPC valve stuck close]: P0457
- Fuel tank pressure ≤ -1.4 kPa (-10.5 mmHg, -0.4 inHg) --> Pass --> move to Mode C
Judgment
- Elapsed time in Mode B ≥ 10000 ms + 25000 ms --> Fail [Fuel cap loose]: P0457
- Fuel tank pressure ≤ -1.4 kPa (-10.5 mmHg, -0.4 inHg) --> Pass --> move to Mode C
- 0.040 inch leak check
0.040 inch evaporative leak monitor is executed through Mode A to Mode D of Monitor 1. The engine lowers the fuel tank pressure using intake manifold vacuum via the canister purge operation during engine running. Once the tank pressure reaches a calibrated target (below atmospheric pressure) the purge valve is closed and the fuel tank pressure is monitored. The pressure transition over a calibrated time period is then used to determine if the fuel tank system has a leak.
Judgment
- evpp2 -- 1.5 x evpp1 > Map 1 --> Fail [0.040 inch Leak]: P0442
- evpp2 -- 1.5 x evpp1 ≤ Map 1 --> Pass [No Leak]
- Monitor 2 (first idle condition)
0.020 inch leak check at first idle condition
An intrusive evaporative leak monitor test is run following the first engine start after a calibrated engine soak period. The engine lowers the fuel tank pressure using intake manifold vacuum via the purge valve operation during engine idle. Once the tank pressure reaches a calibrated target (below atmospheric pressure) the purge valve is closed and the fuel tank pressure is monitored. The pressure transition over a calibrated time period is then used to determine if the fuel tank system has a leak.
- Monitor 2 (vehicle running condition)
0.020 inch Monitor during Vehicle Running (moving) Conditions
While the vehicle is vehicle running, the diagnostic intrusively pulls-down the fuel tank pressure using manifold vacuum via the purge valve. Once the tank pressure reaches a calibrated target (below atmospheric pressure) the purge valve is closed and the fuel tank pressure is monitored. The pressure transition over a calibrated time period is then used to determine if the fuel tank system has a leak.
Judgment
- ptepap1sum > Map 11 --> Fail [0.020 inch Leak]: P0456
- ptepap1sum ≤ Map 12 --> Pass [No Leak]