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In the process of diagnosis, if the device shows "System is OK" or "No Trouble Code", it means there is no related
trouble code stored in ECU or some troubles are not under the control of ECU, most of these troubles are mechanical
system troubles or executive circuit troubles, it is also possible that signal of the sensor may bias within limits,
which can be judged in Live Data.
◼
Clear Trouble Code
It allows clearing current and historical trouble codes memory in ECU, under the premise that all the troubles
are eliminated. There are two types of fault codes, one is a permanent fault code and the other is a non-
permanent fault code. The former requires manual troubleshooting of the car before it can be cleared with a
diagnostic tool. Non-permanent fault codes can be cleared directly with the diagnostic tool.
The trouble codes can't be erased without eliminating all the troubles, which will cause the diagnostic tool to
always read the trouble code because the code will always be saved in ECU.
◼
Read Live Data
That is to read the parameters of the running engine, such as oil pressure, temperature, engine speed, fuel oil
temperature, coolant temperature, intake air temperature, etc. Based on these parameters, we can judge
directly where the problem lies, which helps to narrow the scope of maintenance. For some vehicles, during
their actual operation, the problems such as performance characteristics offset, and sensitivity reduction can
be judged in live data.
In the process of diagnosis, if the device shows "System is OK" or "No Trouble Code", it means there is no
related trouble code stored in ECU or some troubles are not under the control of ECU, most of these troubles
are mechanical system troubles or executive circuit troubles, it is also possible that signal of the sensor may
bias within limits, which can be judged in Live Data.
Figure 4-10 Sample of Clear DTC
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