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DTC P0450 - EVAP Control System Pressure Sensor Malfunction

  1. Remove fuel filler cap. Turn ignition on. Using a voltmeter, measure voltage between ground and PCM harness connector "A", terminal No. 1 (Brown/Red wire). See Figure . If reading is less than 0.5 volt, go to step 4). If reading is 0.5-4.5 volts, go to next step. If reading is greater than 4.5 volts, go to step 6).
  2. Remove tank pressure sensor. Connect three 1.5 volt batteries in series. Connect positive terminal to "Vin" terminal of tank pressure sensor. See Fig 1 . Connect negative terminal to "Ground" terminal. Using a voltmeter, measure voltage between terminals "Vout" and "Ground". Connect a hand-held vacuum pump to tank pressure sensor. As vacuum is applied, voltage reading should decrease. See TANK PRESSURE SENSOR VOLTAGE  table. If reading is as specified, go to next step. If reading is not as specified, replace tank pressure sensor. Retest system.
    Fig 1: Identifying Tank Pressure Sensor Terminals
    G96H09891Courtesy of SUZUKI OF AMERICA CORP.
    TANK PRESSURE SENSOR VOLTAGE

    Applied Vacuum: in. Hg (mm Hg) Output: Voltage
    0 (0) 2.00-2.75
    2 (50) 0.20-0.75
  3. Check system for an intermittent problem. See appropriate TESTS W/O CODES article. Repair as necessary. If system is okay, replace PCM. Retest system.
  4. Turn ignition off. Disconnect tank pressure sensor harness connector. Turn ignition on. Using a voltmeter, measure voltage at Gray/Red wire of connector. If reading is 4.75-5.25 volts, go to next step. If reading is not as specified, check Gray/Red wire for open or short to ground. Repair as necessary. If wire is okay, replace PCM. Retest system. 5) Connect three 1.5 volt batteries in series. Connect positive terminal to "Vin" terminal of tank pressure sensor. See Fig 1 . Connect negative terminal to "Ground" terminal. Using a voltmeter, measure voltage between terminals "Vout" and "Ground". Connect a hand-held vacuum pump to tank pressure sensor. As vacuum is applied, voltage reading should decrease. See TANK PRESSURE SENSOR VOLTAGE  table. If reading is not as specified, replace tank pressure sensor. If reading is as specified, check Brown/Red wire for open or short to ground. Repair as necessary. If wire is okay, replace PCM. Retest system.
  5. Turn ignition off. Disconnect tank pressure sensor harness connector. Turn ignition on. Using a voltmeter, measure voltage between ground and Gray/Red wire of connector. If reading is 4.75-5.25 volts, go to next step. If reading is not as specified, check Gray/Red wire for short to power. Repair as necessary. If wire is okay, replace PCM. Retest system.
  6. Connect three 1.5 volt batteries in series. Connect positive terminal to "Vin" terminal of tank pressure sensor. See Fig 1 . Connect negative terminal to "Ground" terminal. Using a voltmeter, measure voltage between terminals "Vout" and "Ground". Connect a hand-held vacuum pump to tank pressure sensor. As vacuum is applied, voltage reading should decrease. See TANK PRESSURE SENSOR VOLTAGE  table. If reading is not as specified, replace tank pressure sensor. If reading is as specified, check Gray/Red wire for short to Brown/Red wire, or open Gray/Yellow wire. Repair as necessary. If wires are okay, replace PCM. Retest system.
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