3.2L Porsche O2 Sensor fail-safe mode

There is a fail-safe mode for the O2 sensor operation of the 3.2L DME for Porsche. Normally, if the input voltage is below 0.44V, the DME will decide that the mixture ratio is too lean and increase the fuel injection amount. However, if this condition persists for more than 25 seconds, the DME judges that the sensor is abnormal and shifts to the "do nothing" mode to set the correction value back to the center.

If you have short-circuited the O2 sensor terminals in the engine compartment, you may have a slight problem. On cold winter mornings, 25 seconds of rich fuel contributes to ease of starting and stable idle rotation. But when you drop your daughter off at her boyfriend's in the middle of the day in the middle of summer, things are a little different. If you restart the engine and drive away, you will feel the slight upset of too rich fuel and feel a slight shock that will return to normal after 25 seconds.
And while gripping the steering wheel of the MIATA,the boyfriend would say to your daughter, "Your dad's car has too ridh fuel. "The data in the ROM is wrong or the jet nozzle is wrong", "No, the air cleaner might be dirty", "No...", the date is ruined.

What's really important to Dad is that if noise gets into the input terminals of the O2 sensor, there can be a random transition to fail-safe mode or "do nothing" mode.