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Home >> GMC Truck >> 2000 >> S15/T15 Sonoma P/U 2WD L4-2.2L VIN 4 >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> P Code Charts >> P0440

P0440

Schematic:





CIRCUIT DESCRIPTION
The evaporative system includes the following components:
- The fuel tank
- The EVAP vent solenoid
- The fuel tank pressure sensor
- The fuel pipes and hoses
- The fuel vapor lines
- The fuel cap
- The EVAP canister
- The purge lines
- The EVAP canister purge solenoid valve
- The EVAP service port

The evaporative emission system is checked by applying vacuum to the EVAP system and by monitoring for a vacuum decay. The PCM monitors the vacuum level through the fuel tank pressure sensor signal. At an appropriate time, the EVAP canister purge valve and the EVAP vent solenoid are turned ON, allowing the engine to draw a small vacuum on the entire evaporative emission system. After the desired vacuum level has been achieved, the EVAP canister purge valve will turn OFF, sealing the system. DTC P0440 will set because the PCM is not detecting the expected vacuum. This can be caused by the following components with the conditions listed below:
- The fuel cap for the following conditions:
- Missing
- Malfunctioning
- Incorrect
- The fuel tank pressure sensor for the following conditions:
- Disconnected
- Malfunctioning
- The EVAP purge line for the following conditions:
- Disconnected
- Damaged
- Pinched
- Blocked
- The EVAP vent hose for the following conditions:
- Disconnected
- Damaged
- The fuel tank vapor line for the following conditions:
- Disconnected
- Damaged
- Pinched
- Blocked
- The EVAP canister purge solenoid valve for the following conditions:
- Disconnected
- Malfunctioning
- The EVAP vent solenoid for the following conditions:
- Disconnected
- Malfunctioning
- An open ignition feed circuit to the following components:
- EVAP vent valve
- Purge solenoid
- A damaged EVAP canister
- A leaking fuel sender assembly O-ring
- A leak in the following items:
- Fuel tank
- Fuel filler neck

CONDITIONS FOR RUNNING THE DTC
- No active MAP DTCs
- No active IAT DTCs
- No active ECT DTCs
- No active TP DTCs
- No active oxygen sensor DTCs
- No active fuel tank pressure DTCs
- No active VSS DTCs
- No active PCM memory DTCs
- The BARO is more than 75 kPa
- The start-up IAT is between 5°C and 29°C (41°F and 84°F)
- The start-up ECT is between 5°C and 29°C (41°F and 84°F)
- The start-up ECT is less than 8°C (14°F) above the start-up IAT
- The start-up IAT is less than 1.5°C (30°F) above the Start-up ECT
- The fuel tank level is between 15 percent and 85 percent
- The TP sensor is between 7 percent and 35 percent
- The vehicle speed is less than 70 MPH (113 KPH)
- The purge solenoid is enabled

CONDITIONS FOR SETTING THE DTC
The EVAP system is unable to detect vacuum during the diagnostic test.

ACTION TAKEN WHEN THE DTC SETS
- The Malfunction Indicator Lamp (MIL) will illuminate.
- The PCM will record the operating conditions at the time that the diagnostic fails. The Freeze Frame and Failure Records buffers will store this information.
- A history DTC stores.

CONDITIONS FOR CLEARING THE MIL/DTC
- The MIL will turn OFF after one ignition cycle in which the diagnostic runs a pass.
- Freeze Frame information and the history DTC will clear after one ignition cycle in which the diagnostic runs without a fault.
- Use a scan tool to clear the DTC.

DIAGNOSTIC AIDS
Inspect for the following conditions:
- A missing, loose, or damaged fuel cap.
- Missing or damaged O-rings at the EVAP canister fuel vapor fittings and the purge line fittings.
- A cracked EVAP canister.
- Damaged or disconnected source vacuum line, EVAP purge line, vent hose, or fuel tank vapor line.
- A poor connection at the PCM - Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals.
- Damaged harness - Inspect the wiring harness to the EVAP vent solenoid, the EVAP purge solenoid, and the fuel tank pressure sensor for an intermittent, open, or short circuit.
- A kinked, pinched, or plugged vacuum source, EVAP purge, or fuel tank vapor line. Verify that the lines are not restricted.

Inspect for charcoal panicles. Refer to Evaporative Emission (EVAP) System Cleaning before starting repairs. Evaporative Emissions System

Reviewing the fail records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to set occurs. This may assist in diagnosing the condition.

Diagnostic Chart (Part 1 Of 4):




Diagnostic Chart (Part 2 Of 4):




Diagnostic Chart (Part 3 Of 4):




Diagnostic Chart (Part 4 Of 4):





TEST DESCRIPTION
The numbers below refer to the step numbers on the Diagnostic Table.
4. It a vent solenoid or an EVAP canister purge valve electrical malfunction is present, the purge system will not operate correctly. Repairing the electrical malfunction will usually correct the condition that set DTC P0440.
5. This step tests the fuel tank pressure sensor at the ambient pressure
7. This step determines whether or not the EVAP system is sealed sufficiently in order to be pressurized. If the system is not sufficiently sealed, locate and correct the large leak before continuing with the diagnosis.
8. This step verifies that the fuel tank pressure sensor accurately reacts to the EVAP system pressure changes.
12. This step tests for a stuck closed EVAP canister purge solenoid valve.
14. This step ensures that a sufficient source vacuum is present at the EVAP canister purge solenoid valve.
20. This step insures proper system integrity.
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