Critical thinking and reasoning are required when following diagnostic flow charts.

Rob was recently presented with a Mazda CX7 with fault code P205C (Reductant temperature sensor fault). The previous technician got caught out as they didn’t use critical thinking when working through the diagnostic flow chart.
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[@FuManchu5ltr]

I’m amazed the dealership even used a diagnostic flow chart.
Even if the flow chart is flawed, a huge number of people’s automotive problems would not occur if the workshops used the flow chart info.
The strength of the TAT network highlights how important good diagnostic skills are. Parts swapping leads to compromised industry trust.

[@mrblonde2013]

Temp sensor diagnosis; observe live data, disconnect sensor, value should go to around -40 C. Jump the two pins on the connector, the value on the scantool should max out at around 250 C. This proves wiring and ecu are most likely good, replace the temp sensor....10 minute diagnosis.