Part 1 of 2
DTC P0450: Evaporative Emission System Pressure Sensor malfunctionSystem Diagram:
Fuel Tank Differential Pressure Sensor Circuit Part 1:
Fuel Tank Differential Pressure Sensor Circuit Part 2:
CIRCUIT OPERATION
- The ECM (terminal 42)
- The fuel tank differential pressure sensor (terminal 1) returns a voltage signal to the ECM (terminal 93)
TECHNICAL DESCRIPTION
- The ECM
- The ECM
DESCRIPTIONS OF MONITOR METHODS
- Compare purge solenoid status with fuel tank differential pressure sensor output voltage.
MONITOR EXECUTION
- Continuous.
MONITOR EXECUTION CONDITIONS (OTHER MONITOR AND SENSOR)
Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
- Evaporative emission purge solenoid monitor
- Evaporative emission ventilation solenoid monitor
- Fuel level sensor monitor
- Fuel temperature sensor monitor
Sensor (The sensors below are determined to be normal)
- Volume airflow sensor
- Barometric pressure sensor
- Intake air temperature sensor
- Engine coolant temperature sensor
- Accelerator pedal position sensor
LOGIC FLOW CHARTS (Monitor Sequence)
RATIONALITY - HIGH/LOW
LOGIC FLOW CHARTS (Monitor Sequence):
DTC SET CONDITIONS
Check Conditions
- Intake air temperature is greater than 5 degrees C (41 degrees F).
- Engine speed is 1,600 r/min or greater.
- Volumetric efficiency is between 20 and 70 percent.
Judgment Criterion
- When the evaporative emission purge solenoid is off, the fuel differential pressure sensor output voltage remains 1.0 volt or less for ten seconds.
Check Conditions
- Intake air temperature is between 5 degrees C (41 degrees F) and 45 degrees C (113 degrees F) or greater.
- Engine speed is 1,600 r/min or greater.
- Volumetric efficiency is between 20 and 70 percent.
Judgment Criterion
- When the evaporative emission purge solenoid valve is fully operational (100 percent ratio), the fuel differential pressure sensor output voltage remains at 4.0 volts or greater for ten seconds.
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 5 OBD-II Drive Cycle Pattern Lists.
TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THIS CODE TO BE SET ARE:)
- Malfunction of the fuel tank differential pressure sensor.
- A damaged harness in the fuel tank differential pressure sensor circuit.
- Malfunction of the ECM
OVERVIEW OF TROUBLESHOOTING
- DTC P0450 can be set by a faulty fuel tank differential pressure sensor or related circuit, or ECM
- To check for system blockage, do a performance test which uses a mechanical vacuum gauge and scan tool MB991958 set on the fuel tank differential pressure sensor (TANK PRS SNSR 73). The mechanical gauge reading is used to verify scan tool MB991958 reading. A comparison of the mechanical gauge with the reading on scan tool MB991958 will locate a problem in the system.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: MUT-III USB Cable
- MB991911: MUT-III Main Harness B
- MB991658: Test Harness Set
STEP 1. Using scan tool MB991958, check data list item 73: Fuel Tank Differential Pressure Sensor.
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
1. Connect scan tool MB991958 to the data link connector.
2. Disconnect hose G from the evaporative emission canister, and plug the hose.
3. Turn the ignition switch to the "ON" position.
4. Remove the fuel cap.
5. Set scan tool MB991958 to the data reading mode.
- Item 73, Fuel Tank Differential Pressure Sensor.
- The fuel tank pressure reading on the scan tool should be -1.5 to 1.5 kPa (-0.443 to 0.443 in Hg).
6. Connect an evaporative emission system pressure pump (Miller number 6872A) to the fuel filler neck and pressurize the fuel tank.
- The fuel tank pressure reading should increase.
7. Turn the ignition switch to the "LOCK" (OFF) position. Then disconnect scan tool MB991958.
8. Disconnect the evaporative emission system pressure pump, and reinstall the fuel cap.
9. Connect hose G to the canister.
Q: Is the fuel tank pressure between -1.5 and 1.5 kPa (-0.443 and 0.443 inHg)?
YES: It can be assumed that this malfunction is intermittent.Then go to Step 27
NO: Go to Step 2.
STEP 2. Measure the signal voltage at intermediate connector D-14 by backprobing.
1. Disconnect hose G from the evaporative emission canister side, and plug the hose.
2. Remove the rear seat cushion.
3. Pull up the carpet.
4. Turn the ignition switch to the "ON" position.
5. Remove the fuel cap.
6. Measure the voltage between connector D-14 terminal 11 and ground by backprobing.
- The voltage should measure between 2.0 and 3.0 volts.
7. Connect an evaporative emission system pressure pump (Miller number 6872A) to the fuel filler neck and pressurize the fuel tank.
- The fuel tank pressure reading should increase.
8. Turn the ignition switch to the "LOCK" (OFF) position.
9. Disconnect the evaporative emission system pressure pump, and reinstall the fuel cap.
10. Connect hose G to the canister.
Q: Is the measured voltage between 2.0 and 3.0 volts?
YES: Go to Step 3.
NO: Go to Step 7.
STEP 3. Measure the signal voltage at ECM connector C-115
1. Do not disconnect ECM connector C-115
2. Disconnect hose G from the evaporative emission canister side, and plug the hose.
3. Turn the ignition switch to the "ON" position.
4. Remove the fuel cap.
5. Measure the voltage between connector C-115 terminal 93
- The voltage should measure between 2.0 and 3.0 volts.
6. Connect an evaporative emission system pressure pump (Miller number 6872A) to the fuel filler neck and pressurize the fuel tank.
- The fuel tank pressure reading should increase.
7. Turn the ignition switch to the "LOCK" (OFF) position.
8. Disconnect the evaporative emission system pressure pump, and reinstall the fuel cap.
9. Connect hose G to the canister.
Q: Is the measured voltage between 2.0 and 3.0 volts?
YES: Go to Step 4.
NO: Go to Step 5.
STEP 4. Check ECM connector C-115
Q: Are the connectors and terminal in good condition?
YES: Go to Step 26.
NO: Repair or replace the damaged components. Then go to Step 27.
STEP 5. Check intermediate connectors C-124, C-127, D-14 and ECM connector C-115
Q: Are the connectors and terminals in good condition?
YES: Go to Step 6.
NO: Repair or replace the faulty component. Go to Step 27.
STEP 6. Check the harness wire between ECM connector C-115 terminal 93
Q: Is the harness wire in good condition?
YES: It can be assumed that this malfunction is intermittent.Then go to Step 27.
NO: Repair the damaged harness wire. Then go to Step 27.
STEP 7. Measure the 5-volt reference signal at intermediate connector D-14 by backprobing.
1. Do not disconnect intermediate connector D-14.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between connector D-14 terminal 9 and ground.
- The voltage should measure between 4.9 and 5.1 volts.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage between 4.9 and 5.1 volts?
YES: Go to Step 11.
NO: Go to Step 8.
STEP 8. Measure the 5-volt reference signal at ECM connector C-117
1. Do not disconnect ECM connector C-117
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between connector C-117 terminal 42
- The voltage should measure between 4.9 and 5.1 volts.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage between 4.9 and 5.1 volts?
YES: Go to Step 9.
NO: Go to Step 25.
STEP 9. Check intermediate connectors C-105, C-124, C- 127, and D-14 and ECM connector C-117
Q: Are the connectors and terminals in good condition?
YES: Go to Step 10.
NO: Repair or replace the damaged components. Then go to Step 27.
STEP 10. Check the harness wire between ECM connector C-117
Q: Is the harness wire in good condition?
YES: It can be assumed that this malfunction is intermittent. Then go to Step 27.
NO: Repair the damaged harness wire. Then go to Step 27.