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 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 is turned to the OFF (LOCK) mode | 10 seconds | - |
| Engine coolant temperature[ECT Sensor 1] beforeEVAP 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) for at least 10 seconds.
Possible Cause
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 closed stuck
- FTP sensor stuck
- EVAP system line clogged
- EVAP system line misinstalled
Confirmation Procedure
Operating Condition
- 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.
- Let the engine idle for at least 56 seconds.
- Turn the vehicle to the OFF (LOCK) mode, and leave the vehicle for at least 10 seconds.
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, the freeze data, and the on-board snapshot 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, the freeze data, and the on-board snapshot can be cleared with the scan tool clear command.