HHR L4-2.2L (2007)
* The MIL flashes if the control module detects a misfire condition which could damage the catalytic converter.
* When the MIL is illuminated and the engine stalls, the MIL will remain illuminated as long as the ignition is ON.
* When the MIL is not illuminated and the engine stalls, the MIL will not illuminate until the ignition is cycled OFF and then ON.
Warm-up Cycle
The ECM uses warm-up cycles to run some diagnostics and to clear any diagnostic trouble codes (DTCs). A warm-up cycle occurs when the engine
coolant temperature increases 22°C (40°F) from the start-up temperature. The engine coolant must also achieve a minimum temperature of 71°C (160°F)
. The ECM counts the number of warm-up cycles in order to clear the malfunction indicator lamp (MIL). The ECM will clear the DTCs when 40
consecutive warm-up cycles occur without a malfunction.
Diagnostic Trouble Codes (DTCs)
The ECM is programmed with test routines that test the operation of the various systems the ECM controls. Some tests monitor internal ECM functions.
Many tests are run continuously. Other tests run only under specific conditions, referred to as Conditions for Running the DTC. When the vehicle is
operating within the conditions for running a particular test, the ECM monitors certain parameters and determines if the values are within an expected
range. The parameters and values considered outside the range of normal operation are listed as Conditions for Setting the DTC. When the Conditions
for Setting the DTC occur, the ECM executes the Action Taken When the DTC Sets. Some DTCs alert the driver via the MIL or a message. Other DTCs
do not trigger a driver warning, but are stored in memory. The ECM also saves data and input parameters when most DTCs are set. This data is stored in
the Freeze Frame and/or Failure Records.
The DTCs are categorized by type. The DTC type is determined by the MIL operation and the manner in which the fault data is stored when a particular
DTC fails. In some cases there may be exceptions to this structure. Therefore, when diagnosing the system it is important to read the Action Taken When
the DTC Sets and the Conditions for Clearing the DTC in the supporting text.
There are different types of DTCs and different actions taken when the DTCs set. Refer to Diagnostic Trouble Code (DTC) Type Definitions for a
description of the general characteristics of each DTC type.
