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DTC P1438: Fuel Tank Pressure too High
 
 
 
 
TECHNICAL DESCRIPTION
  • The engine control module monitors the signals input from the fuel tank pressure sensor.
  • Based on The input signals, the engine control module checks whether the pressure in the fuel tank exceeds the maximum withstand pressure of the system.
 
 
DTC SET CONDITIONS
Check Condition
  • Power supply mode of electric motor switch is ON.
Judgment Criterion
  • Fuel tank pressure is more than 48 kPa for 4 seconds.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • None
 
 
TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THIS CODE TO BE SET ARE:)
  • Vapor line or purge line is clogged.
  • Fuel tank solenoid valve failed.
  • Fuel tank pressure sensor failed.
  • Fuel tank pressure sensor circuit harness damage, or connector damage.
  • Evaporative emission purge solenoid failed.
  • Barometric pressure sensor failed.
  • ECM failed.
 
 
DIAGNOSIS
STEP 1. Using scan tool (M.U.T.-IIISE), read the diagnostic trouble code (DTC).
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn off the power supply mode of the electric motor switch before connecting or disconnecting scan tool (M.U.T.-IIISE).
(1) Connect scan tool (M.U.T.-IIISE). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-IIISE) .
(2) Turn on the power supply mode of the electric motor switch.
(3) Read the DTC.
(4) Turn off the power supply mode of the electric motor switch.
Is the diagnostic trouble code other than P1438 set?
Refer to Diagnostic Trouble Code Chart .
Go to Step 2.
 
STEP 2. Using scan tool (M.U.T.-IIISE), check data list item 211: Fuel Tank Pressure Sensor.
(1) Turn on the power supply mode of the electric motor switch.
(2) Remove the fuel cap.
(3) Set scan tool (M.U.T.-IIISE) to the data reading mode for item 211, Fuel Tank Pressure Sensor.
  • When altitude is 0 m (0 foot), 101 kPa (29.8 in.Hg).
  • When altitude is 600 m (1,969 feet), 95 kPa (28.1 in.Hg).
  • When altitude is 1,200 m (3,937 feet), 88 kPa (26.0 in.Hg).
  • When altitude is 1,800 m (5,906 feet), 81 kPa (23.9 in.Hg).
(4) Turn off the power supply mode of the electric motor switch.
Is the sensor operating properly?
Go to Step 5.
Go to Step 3.
 
STEP 3. Check of harness damage in F/PR, FPRE and FPR5 line between fuel tank pressure sensor connector and ECM connector.
Is the harness wire in good condition?
Go to Step 4.
Repair the connector(s) or wiring harness. Then go to Step 9.
 
STEP 4. Replace the fuel tank pressure sensor.
(1) Replace the fuel tank pressure sensor.
(2) Turn on the power supply mode of the electric motor switch.
(3) After the DTC has been deleted, read the DTC again.
(4) Turn off the power supply mode of the electric motor switch.
Is DTC P1438 set?
Replace the ECM (Refer to Removal and Installation ). Then go to Step 9.
The inspection is complete.
 
STEP 5. Check for clogs in evaporative emission hose H.
(1) Drain the fuel from the fuel tank.
(2) Use a hand vacuum pump to check hose H.
Is there hose ventilation?
Go to Step 6.
Repair it. Then go to Step 9.
 
STEP 6. Check the relief valve of fuel tank solenoid valve for clogs.
Refer to GROUP 17, Emission Control - Evaporative Emission Control System - Fuel Tank Solenoid Valve Check .
Is the relief valve operating properly?
Go to Step 7.
Replace the fuel tank solenoid valve. Then go to Step 9.
 
STEP 7. Check piping clogging between the evaporative emission purge solenoid and fuel tank solenoid valve.
(1) Disconnect the shown hose E in the fuel tank solenoid valve.
(2) Disconnect the shown hose A from evaporative emission purge solenoid and mount the hand vacuum pump on the hose side.
  • When negative pressure is applied with the hand vacuum pump, check that there is ventilation and no clogging.
Are the hoses and pipes in good condition?
Go to Step 8.
Repair the hose(s) or pipe(s). Then go to Step 9.
 
STEP 8. Check the evaporative emission purge solenoid for clogs.
Refer to GROUP 17, Emission Control - Evaporative Emission Control System - evaporative emission purge solenoid Check .
Is there ventilation of the evaporative emission purge solenoid?
Replace the ECM (Refer to Removal and Installation ). Then go to Step 9.
Replace the evaporative emission purge solenoid. Then go to Step 9.
 
STEP 9. Using scan tool (M.U.T.-IIISE), read the diagnostic trouble code (DTC).
(1) Turn on the power supply mode of the electric motor switch.
(2) After the DTC has been deleted, read the DTC again.
(3) Turn off the power supply mode of the electric motor switch.
Is DTC P1438 set?
Retry the troubleshooting.
The inspection is complete.