DTC P04DF

DTC P04DF:  Evaporative Emission (EVAP) System High Purge Flow Detected

General Description 

Courtesy of HONDA, U.S.A., INC.

Courtesy of HONDA, U.S.A., INC.

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 EVAP leak check module pressure 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 EVAP leak check module pressure 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 EVAP leak check module pressure 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 EVAP leak check module pressure 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 EVAP leak check module pressure 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 engine is stopped	10 seconds	-
Engine coolant temperature [ECT Sensor 1] before EVAP purge control starts	104 deg.F (40 deg.C)	-

[ ]: HDS Parameter

Malfunction Threshold 

The output from the FTP sensor [FTP Sensor] is 0.27 kPa (2.00 mmHg, 0.079 inHg) or more.

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 open stuck
• EVAP canister purge valve 1 middle stuck

Confirmation Procedure 

Operating Condition 

• 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, then let it idle.
• Let the engine running for at least 30 seconds.
• Stop the engine and leave the vehicle for at least 10 seconds.

With the HDS 

Select the EVAP TEST in the Function Test Menu, then select EVAP Leak Check Module 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.