DTC P145C

DTC P145C:  Evaporative Emission (EVAP) System Purge Flow Malfunction

General Description 

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.

<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 (P145C OK)

• P0497 Purge flow OK
• P0496 EVAP canister purge valve stuck Open OK

NG determination: No pulse (P145C NG)

• Either purge flow P0497 abnormality or P0496 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: P0496 EVAP canister purge valve stuck OPEN

When there is no fluctuation of the FTP sensor: P0497 purge flow NG

Monitor Execution, Sequence, Duration, DTC Type 

Execution	Once per driving cycle
Sequence	None
Duration	18 seconds or more
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	140 deg. F (60 deg. C)* 1, 131 deg. F (55 deg. C)* 2	-
MAP value [MAP SENSOR]	-	-47 kPa (-13.8 inHg, -350 mmHg)
12 volt battery voltage [BATTERY]	10.5 V	-
Fuel trim	0.69	1.47
EVAP canister purge valve duty [EVAP PC DUTY]	30 %	80 %
Fuel feedback	Closed loop at stoichiometric

*1: M/T model

*2: CVT model

[ ]: HDS Parameter

Malfunction Threshold 

The pulses detected by the FTP sensor are 50 % or less for at least 18 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 closed stuck
• EVAP canister purge valve open stuck
• FTP sensor output 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 (CVT in P or N, M/T in neutral) until the radiator fan comes on.
• Let the engine idle for at least 63 seconds.
• Turn the vehicle to the OFF (LOCK) mode and leave the vehicle for at least 10 seconds.

With the HDS 

None.

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.