P0442

DTC P0442 EVAP System Leak Detected




Circuit Description
The evaporative system includes the following components:
- Fuel tank
- EVAP canister vent solenoid
- Fuel tank pressure sensor
- Fuel pipes and hoses
- Vapor lines
- Fuel cap
- Evaporative emissions canister
- Purge lines
- EVAP canister purge solenoid

The evaporative leak detection diagnostic strategy is based on applying vacuum to the EVAP system and monitoring vacuum decay. The powertrain control module (PCM) monitors vacuum level via the fuel tank pressure sensor input. At an appropriate time, the EVAP canister purge solenoid and the EVAP canister vent solenoid are turned ON, allowing engine vacuum to draw a small vacuum on the entire evaporative emissions system. After the desired vacuum level has been achieved, the EVAP canister purge solenoid is turned OFF sealing the system. A leak is detected by monitoring for a decrease in vacuum level over a given time period, all other variables remaining constant. A small leak in the system will cause DTC P0442 to be set.

Conditions for Setting the DTC
- No TP sensor, 0DM, IAT sensor, or MAP sensor DTCs set.
- The DTC P0440 diagnostic test has passed.
- A vacuum decay condition, indicating a small leak, is detected during the diagnostic test.

Action Taken When the DTC Sets
- The PCM will illuminate the malfunction indicator lamp (M IL) during the second key cycle in which the DTC sets.
- The PCM will store conditions which were present when the DTC was set as Freeze Frame and in the Failure Records data.

Conditions for Clearing the MIL/DTC
- The PCM will turn the MIL OFF on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present.
- A history DTC P0442 will clear after 40 consecutive warm-up cycles have occurred without a fault.
- DTC P0442 can be cleared by using the scan tool Clear Info tunction or by disconnecting the PCM battery feed.

Diagnostic Aids
Check for the following conditions:
-Cracked or punctured EVAP canister.
-Damaged source vacuum line, EVAP purge line, EVAP vent hose or fuel tank vapor line.
-Poor connection at PCM - Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
-Damaged harness-Inspect the wiring harness to the EVAP canister vent solenoid, EVAP canister purge solenoid and the fuel tank pressure sensor for an intermittent open or short circuit.
Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

Steps 1 - 4:

Steps 4 - 8:

Steps 9 - 11:

Test Description
Number(s) below refer to the step number(s) on the Diagnostic Chart.
2. If an EVAP canister vent solenoid or an EVAP canister purge solenoid electrical fault is present, the purge system will not operate correctly. Repairing the electrical fault will very likely correct the condition that set DTC P0442.
3. Checks the fuel tank pressure sensor at ambient pressure.
4. Verifies that the fuel tank pressure sensor accurately reacts to EVAP system pressure changes.