DTC Advanced Diagnostics: P04F1
DTC P04F1:Evaporative Emission (EVAP) System Low Purge Flow Detected

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.

<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).

OK determination: Pulse exists (P0441 OK)
P04F1 Purge flow OK
P04DF EVAP canister purge valve stuck Open OK

NG determination: No pulse (P0441 NG)
Either purge flow P04F1 abnormality or P04DF EVAP canister purge valve OPEN failure
In this case, classify the failed part according to <STEP 2>

<STEP 2>

If there is no pulse, it is determined as either no purge flow or the EVAP canister purge valve is stuck OPEN:

When the FTP sensor fluctuates from negative pressure to atmospheric pressure after the vehicle condition is turned to the OFF (LOCK) mode: P04DF EVAP canister purge valve stuck OPEN

When there is no fluctuation of the FTP sensor: P04F1 purge flow NG

Monitor Execution, Sequence, Duration, DTC Type
Execution
Once per driving cycle
Sequence
P0441 is judged as NG
Duration
–
DTC Type
Two drive cycles, MIL on

Enable Conditions
Condition
Minimum
Maximum
Low load duration time
10 seconds
–
Wait for stability after the vehicle condition is turned to the OFF (LOCK) mode
10 seconds
–
Engine coolant temperature [ECT SENSOR 1] before EVAP purge control starts
131 °F (55 °C)
–
[ ]: HDS Parameter

Malfunction Threshold
The output from the FTP sensor [FTP SENSOR] is less than 0.2 kPa (2 mmHg, 0.07 inHg).

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.
FTP sensor stuck
EVAP system line clogged
EVAP system line misinstalled
EVAP canister purge valve open stuck

Confirmation Procedure
Operating Condition
1.
Start the engine. Hold the engine speed [ENGINE SPEED] at 3,000 rpm without load (CVT in P or N, M/T in neutral) until the radiator fan comes on.
2.
Let the engine idle for at least 64 seconds.
3.
Turn the vehicle to the OFF (LOCK) mode and leave the vehicle for at least 10 seconds.
With the HDS
Select the EVAP TEST in the INSPECTION MENU, then select the FUNCTION TEST 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.