The OBDII Diagnostics window displays information obtained from the vehicle OBDII interface.
DTCs
DTCs (diagnostic trouble codes) or error codes are set by the ECU to indicate a problem with a system or component. DTCs are expressed as a four digit code, usually starting with a 'P' (for power train) related problems.
If you have any DTCs, then these should be fixed before proceeding with any vehicle tuning. For information on diagnosing and fixing DTCs, see you vehicle service manual. Normally there is a trouble shooting and fault diagnostic procedure for each DTC.
Readiness Codes
Readiness codes are part of the vehicle OBDII system, which indicate if the various emissions components have been tested by the ECU.
Readiness codes are either continuously monitored or monitored once per trip. Continuously monitored codes are checked by the ECU all the time. Current continuously monitored codes are:
| • | Misfire monitoring |
| • | Fuel system monitoring |
| • | Comprehensive component monitoring |
Non-continuously (or trip) monitored codes are checked by the ECU under specific conditions, which may be over several trips. See the vehicle service manual for information on how to set the vehicle readiness codes. Current non-continuous monitored codes are:
| • | Catalyst monitoring |
| • | Heated catalyst monitoring |
| • | Evaporative system monitoring |
| • | Secondary air system monitoring |
| • | A/C system refrigerant monitoring |
| • | Oxygen sensor monitoring |
| • | Oxygen sensor heater monitoring |
| • | EGR system monitoring |
Not all readiness codes are supported by all vehicles. If a test is marked as not supported then this does not mean there is a problem with that system.
If the ECU is re-programmed, DTCs are cleared, the ECU removed, or the battery is disconnected, then the readiness codes are all reset to 'incomplete'.
Parameters
This displays OBDII datalogging parameters.
Information
This shows other information obtained via the OBDII interface.
Emissions Check
This simulates the emissions test used by most emission testing stations. Note that each State or County may have different requirements to pass an emissions test.
State emissions tests usually check three items at a minimum:
| • | If the MIL is on or off. |
| • | How many DTCs are set. |
| • | Readiness monitor status. |
Each State will have different requirements, by generally in order to pass the State emission test:
| • | The MIL must not be commanded on. |
| • | No DTCs must be set. |
| • | The readiness codes must be all complete or almost all complete. |
If readiness codes are marked as incomplete then see your vehicle service manual for information on how to perform the readiness monitor driving cycles to complete testing.
Automatic Refresh
When checked, auto refresh continuously refreshes the information displayed in the OBDII window.