DTC P04F1: Evaporative Emission (EVAP) System Low Purge Flow Detected (2017)
General Description
The fuel vapor in the fuel tank is temporarily stored in the evaporative emission (EVAP) canister and drawn into the engine through the EVAP canister purge valve. The powertrain control module (PCM) controls the amount of vapor introduced into the engine by varying the duty cycle of the EVAP canister purge valve according to the condition of the engine. The EVAP system is a system which has this EVAP canister purge valve equipped parallel and adjusts the amount of vapor by driving the EVAP canister purge valve 2 when the EVAP canister purge valve 1 is fully opened.
<STEP 1>
The EVAP canister purge valve opens normally (EVAP canister purge valve OPEN OK) and detects that the purge flow is normal when the pulse of the EVAP canister purge valve duty cycle is transmitted to the fuel tank pressure (FTP) sensor during purge flow (pulse method). If there are no pulsation with EVAP canister purge valve 1, it judges pulsation by switching to EVAP canister purge valve 2 drive in EVAP canister purge valve 1 drive area.
OK determination: If pulsation from EVAP canister purge valve 1 drive area and pulsation from EVAP canister purge valve 2 area (EVAP canister purge valve 1 is in fully opened driving condition) are both present. (P0441 OK / P145E OK)
- P04F1 Purge flow OK
- P04DF EVAP canister purge valve 1 stuck Open OK
- P04AE EVAP canister purge valve 2 stuck Open OK
NG determination: If pulsation from EVAP canister purge valve 1 drive area is not present but pulsation from EVAP canister purge valve 2 drive is present. (P0441 NG/ P145E OK)
- Either purge flow P04F1 abnormality or P04DF EVAP canister purge valve 1 OPEN failure.
- In this case, classify the failed part according to <STEP 2>.
NG determination: If pulsation from EVAP canister purge valve 2 drive area is not present but pulsation from EVAP canister purge valve 1 drive is present. (P0441 OK/ P145E NG)
- Either purge flow P04F1 abnormality or P04DF EVAP canister purge valve 1 OPEN failure.
NG determination: If pulsation from EVAP canister purge valve 1 and EVAP canister purge valve 2 drive area is not present. (P0441 NG/ P145E NG)
- P04F1 Purge flow NG
<STEP 2>
If there is no pulse, it is determined as either no purge flow or the EVAP canister purge valve 1 is stuck OPEN:
When the FTP sensor fluctuates from negative pressure to atmospheric pressure after the engine stopped : P04DF EVAP canister purge valve 1 stuck OPEN
When there is no fluctuation of the FTP sensor: P04F1 purge flow NG
If there is no pulse, it is determined as either no purge flow or the EVAP canister purge valve 2 is stuck OPEN:
When the FTP sensor fluctuates from negative pressure to atmospheric pressure after the engine stopped : P04AE EVAP canister purge valve 2 stuck OPEN
When there is no fluctuation of the FTP sensor: P04F1 purge flow NG
Monitor Execution, Sequence, Duration, DTC Type, OBD Status
| Execution | Once per driving cycle |
| Sequence | P0441, P145E is judged as NG |
| Duration | - |
| DTC Type | Two drive cycles, MIL on |
| OBD Status | PASSED/FAILED/NOT COMPLETED (STILL TESTING) |
Enable Conditions
| Condition | Minimum | Maximum |
|---|---|---|
| Low load duration time | 10 seconds | - |
| Wait for stability after the engine stopped | 10 seconds | - |
[ ]: HDS Parameter
| Condition | Minimum | Maximum |
|---|---|---|
| Engine coolant temperature [ECT SENSOR 1] before EVAP purge control starts | 104 °F (40 °C) | - |
[ ]: HDS Parameter
Malfunction Threshold
The output from the FTP sensor [FTP SENSOR] is less than 0.2 kPa (0.07 inHg, 2 mmHg) for at least 10 seconds.
Possible Cause
NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
- EVAP canister purge valve 1 close stuck
- EVAP canister purge valve 2 close stuck
- EVAP canister purge valve 1 middle stuck
- EVAP canister purge valve 2 middle stuck
- FTP sensor stuck
- EVAP system line clogged
- EVAP system line misinstalled
Confirmation Procedure
Operating Condition
- 1.
Enter the maintenance mode, then start the engine. Hold the engine speed [ENGINE SPEED] at 3, 000 rpm without load (in P or N) until the radiator fan comes on.
- 2.
Let the engine running for at least 30 seconds.
- 3.
Engine stopped and leave the vehicle for at least 10 seconds.
With the HDS
Do the EVAP FUNCTION TEST in the INSPECTION MENU with the HDS.
Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle, 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 12 volt battery.