DTC Advanced Diagnostics: P2450
DTC P2450:Evaporative Emission (EVAP) System Purge Line Non-return Valve A Stuck Open

General Description



Negative side purge flow
Boost side purge flow
Purge back-flow (P2450)
Condition
Flowing
Flowing
OK
Purge line normal, EVAP canister purge valve normal
Flowing
Flowing
NG (P2450)
Non-return valve A abnormal
Not flowing
Flowing
–
Negative side purge line abnormal
Flowing
Not flowing
–
Boost side purge line abnormal
Not flowing
Not flowing
–
Purge line abnormal, EVAP canister purge valve open

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 PCM checks the purge flow conditions on both negative and boost pressure sides. If either side of the purge flow is detected as abnormal, it is determined that there is a clog or disconnection on the abnormal side of the purge line. If both sides of the purge flow are detected as abnormal, it is determined that the purge lines are abnormal or the EVAP canister purge valve is stuck opened.

If non-return valve A is stuck opened, the boost pressure flows back to the fuel tank when purge controlled in boost condition. At the time, the FTP sensor pulse waveform shows opposite phase to the usual phase. The PCM detects a malfunction by calculating the phase time difference, and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type
Execution
Once per driving cycle
Sequence
None
Duration
–
DTC Type
Two drive cycles, MIL on

Enable Conditions
Condition
Minimum
Maximum
Low load duration time
10 seconds
–
Engine coolant temperature [ECT SENSOR 1] before EVAP purge control starts
131 °F (55 °C)
–
MAP value [MAP SENSOR]
–
81 kPa (610 mmHg, 24.0 inHg)
12 volt battery voltage [BATTERY]
10.5 V
–
Fuel trim
0.75
1.47
EVAP canister purge valve duty [EVAP PC DUTY]
30 %
80 %
Fuel feedback
Closed loop at stoichiometric
[ ]: HDS Parameter

Malfunction Threshold
The FTP sensor pulse phase time difference is 20 milliseconds 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.
Non-return valve A open stuck

Confirmation Procedure
Operating Condition
1.
Start the engine. Hold the engine speed [ENGINE SPEED] at 3,000 rpm without load (in neutral) until the radiator fan comes on.
2.
Let the engine idle for at least 55 seconds.
3.
Drive the vehicle at high load for total of at least 9.5 seconds.
4.
Turn the vehicle to the OFF (LOCK) mode and leave the vehicle for at least 10 seconds.
Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.
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.