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An exhaust gas temperature gauge (EGT gauge or EGT sensor) is a meter used to monitor the exhaust gas temperature of an internal combustion engine in conjunction with a thermocouple-type pyrometer. EGT gauges are found in certain cars and aeroplanes. By monitoring EGT, the driver or pilot can get an idea of the vehicle's air-fuel ratio (AFR).

At a stoichiometric air-fuel ratio, the exhaust gas temperature is different from that in a lean or rich air-fuel ratio. At rich air-fuel ratio, the exhaust gas temperature either increases or decreases depending on the fuel. High temperatures (typically above 1,600 °F or 900 °C) can be an indicator of dangerous conditions that can lead to catastrophic engine failure.


Oxygen sensor

Using an EGT meter alone is considered an older technique for getting the most out of petrol and diesel engines,[according to whom?] as gauge-type wideband digital oxygen sensors are similarly priced.[where?] However, some advanced racers[example needed] will use EGT gauges in combination with a wideband oxygen sensor to lean the fuel ratio a bit to safely raise the temperature for more power.[citation needed]

Advanced tuning

Though by tuning primarily by EGT and air fuel ratio values, EGT is still to this day a used data output for engine tuning. When fine tuning an engine, if possible with the ECU manipulation with the cylinder's timing can be made. By adjusting the timing, the resultant cylinder temperature can be used to improve cylinder efficiency. Though this is still widely done,[timeframe?] EGT values should be used as a safe guard sensor measure and as a tuning guide.[citation needed]


  1. ^ Mike Busch. "EGT Myths Debunked". Retrieved 2019-05-19.
  2. ^ "No. 2558: Cooled by Air or Water". Archived from the original on 9 August 2017. Retrieved 30 April 2018.