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stin1974, Auto Service Technician
Category: Car
Satisfied Customers: 765
Experience:  Domestic transmission diagnostics and troubleshooting. General repair diagnostics and troubleshoot.
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The check engine light on my 2004 Saturn Ion recently came

Resolved Question:

The check engine light on my 2004 Saturn Ion recently came on. I ran a diagnostic test on it and the code that came up is P0442. (Evap System Small Leak). Do you have any ideas on what options I have to try to fix it?
Submitted: 8 years ago.
Category: Car
Expert:  stin1974 replied 8 years ago.
2.0 or 2.2?
Customer: replied 8 years ago.
What additional information do you need? Also, as this trouble with my vehicle came up, my Change Oil light came on as well. It has only been 2 months maximum since I changed it.
Expert:  stin1974 replied 8 years ago.
Is this motor a 2.0 or a 2.2 motor?
Customer: replied 8 years ago.
I'm sorry but I don't know what other information you need? Could you tell me exactly what you need to know?
Expert:  stin1974 replied 8 years ago.
Sometimes this code will set if you refuel while the vehicle is running in which case you can just clear the codes. Also a bad gas cap is often the problem. This should show you all the trouble shooting procedures though.
stin1974 and 3 other Car Specialists are ready to help you
Expert:  stin1974 replied 8 years ago.

DTC P0442

This DTC tests the evaporative emission (EVAP) system for a small leak. The control module monitors the fuel tank pressure (FTP) sensor signal to determine the vacuum decay rate. At an appropriate time, the control module turns the EVAP canister purge solenoid valve ON and the EVAP canister vent solenoid valve ON. This allows the engine to draw a vacuum on the EVAP system. At a calibrated time, or vacuum level, the control module turns the EVAP canister purge solenoid valve OFF, sealing the system, and monitors the FTP sensor input in order to determine the EVAP system vacuum decay. If the control module detects a leak larger than a calibrated amount, this DTC sets.

The table illustrates the relationship between the ON and OFF states, and the Open or Closed states of the EVAP canister purge and vent solenoid valves.

This diagnostic supports the following DTC:
DTC P0442 Evaporative Emissions (EVAP) System Small Leak Detected


  • DTCs P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0452, P0453, P0500, P0601, P0602, P0606, P0641 are not set.
  • The ignition voltage is between 11-18 volts .
  • The barometric pressure (BARO) is more than 74 kPa .
  • The fuel level is between 15-44 percent for a 0.040 inch leak and 44-85 percent for a 0.020 inch leak.
  • The engine coolant temperature (ECT) is between 5-32°C (41-90°F) .
  • The intake air temperature (IAT) is between 5-32°C (41-90°F) .
  • The start up ECT and IAT are within 9°C (16°F) of each other.
  • The engine run time is less than 600 seconds .
  • No vehicle speed DTCs are set in the transmission control module (TCM).

The EVAP system can achieve vacuum but a vacuum decay is detected during the diagnostic test.


  • The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
  • The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.


  • The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
  • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
  • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
  • Clear the MIL and the DTC with a scan tool.


  • A leak in the EVAP system can be verified by the use of the flow meter on the J 41413-200 (J 41413-100) Evaporative Emissions System Tester (EEST). Refer to the J 41413-200 (J 41413-100) operation manual for flow meter use.
  • To help locate intermittent leaks, use the J 41413-200 (J 41413-100) to introduce smoke into the EVAP system. Move all EVAP components while observing smoke with the High Intensity White Light.
  • To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with a High Intensity White Light.
  • A condition may exist where a leak in the EVAP system only exists under a vacuum condition. By using the scan tool PURGE/SEAL function to create a vacuum, seal the system and observe the FTP parameter for vacuum decay, this type of leak may be detected.
  • For intermittent conditions, refer to Intermittent Conditions. See: Initial Inspection and Diagnostic Overview\Diagnostic Strategies\Intermittent Conditions


Steps 1-4

Steps 5-6

The numbers below refer to the step numbers on the diagnostic table.

  1. Introducing smoke in 15 second intervals may allow smaller leak areas to be more noticeable. When the system is less pressurized, the smoke will sometimes escape in a more condensed manner.
  1. This step verifies that repairs are complete and that no other condition is present.