DTC P0464: Fuel Level Sensor Circuit Intermittent

Detect the malfunction of unstable output from fuel level sensor because of noise.

Judge NG by comparing the max value and cumulative value of the amount of output voltage variation from fuel level sensor with threshold value.

Perform the diagnosis continuously at idling.

Calculate the max. value of the amount of output voltage variation from fuel level sensor and cumulative value during 12.8 seconds. Comparing the max value and cumulative value with the threshold value, and judge OK when the both do not go over the threshold value. Otherwise, when one of them goes over the threshold, count the counter up. Judge the ECM is troubled when the counter increased 4 times in a row.

Fig 1: Judge ECM Is Troubled When Counter Increased 4 Times In Row Graf

Courtesy of SUBARU OF AMERICA, INC.

• Abnormality Judgment 

  Judge NG when the malfunction criteria below are completed.

  Judgment Value 

  JUDGMENT VALUE
  
  

  Malfunction Criteria	Threshold Value
  Integrated times of the condition reaching follows, DVFLMAX "GREATER THAN EQUAL TO" 0.88 V SUMVFL "GREATER THAN EQUAL TO" 14.08 V DVFLMAX is max. value of sensor output during 12.8 seconds. SUMVFL is cumulative value of sensor output deviation during 12.8 seconds	"GREATER THAN EQUAL TO" times

  Time Needed for Diagnosis:  12.8 seconds x 4 times

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

• Normality Judgment 

  Judge OK and clear the NG when all the malfunction criteria below are completed.

  Judgment Value 

  JUDGMENT VALUE
  
  

  Malfunction Criteria	Threshold Value
  DVFLMAX	< 0.88 V
  SUMVFL	< 14.08 V

• When the OK idling cycle is completed 40 times in a row
• When "Clear Memory" was performed

• When the OK driving cycle is completed 3 times in a row
• When "Clear Memory" was performed

None

Memorize the freeze frame data. (For test mode $02)