DTC P1446: Fuel Tank Sensor Control Valve Circuit Low

OUTLINE OF DIAGNOSIS
- Detect the open/short circuit of fuel tank sensor control valve.
- Judge NG when the ECM output level is different from actual terminal level.
COMPONENT DESCRIPTION

Fig 1: Identifying Fuel Tank Sensor Control Valve (Low Circuit)
Courtesy of SUBARU OF AMERICA, INC.

ENABLE CONDITION

Secondary Parameters	Enable Conditions
Engine speed	"GREATER THAN EQUAL TO" 500rpm
Battery voltage	"GREATER THAN EQUAL TO" 8 V
After engine starting	1 second or more
Ignition switch	ON

GENERAL DRIVING CYCLE
Perform the diagnosis continuously after starting the engine.

DIAGNOSTIC METHOD

Judge NG when the continuous time until completing the malfunction criteria below becomes more than the time (2.5 seconds) needed for diagnosis. Judge OK and clear the NG when the malfunction criteria are not completed.

Judgment Value

JUDGMENT VALUE

Malfunction Criteria	Threshold Value
Terminal voltage level when ECM sent OFF signals	Low level

Time Needed for Diagnosis: 2.5 seconds

Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cycles.

DTC CLEAR CONDITION
- When the OK idling cycle is completed 40 times in a row
- When "Clear Memory" was performed
MALFUNCTION INDICATOR LIGHT CLEAR CONDITION
- When the OK driving cycle is completed 3 times in a row
- When "Clear Memory" was performed
FAIL SAFE
None
ECM OPERATION AT DTC SETTING
Memorize the freeze frame data. (For test mode $02)