AIR FUEL RATIO (A/F) SENSOR HEATER CONTROL [SKYACTIV-G 2.5T]

id0140h0785500

Outline

• Performs duty control of the heater according to the engine operation conditions (exhaust gas temperature) for A/F sensor protection and enhanced emission performance.

• By controlling the A/F sensor heater, stable detection of oxygen concentration is possible even with low exhaust gas temperature, and feedback control for the fuel injection control is possible even after cold engine start, enhancing the emission performance under cold temperatures.

• A pre-heat has been adopted to prevent water, (produced from the exhaust system when the engine is started), from adhering to the sensor and damaging it.

Block Diagram

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Operation

Pre-heat control

• The A/F sensor heater is operated at a duty ratio of approx. 15 % within the specified time directly after the engine is started.

Normal control

• The PCM operates the A/F sensor heater based on the following control conditions:

Output duty ratio

Control condition

0 %

•  Ignition switched off

•  Engine stopped

•  Engine start (cranking)

0―100 %

(Duty ratio determined by measuring the element temperature by the A/F sensor heater element impedance)

•  After engine warm-up (such as value fluctuates by battery condition)

Output duty ratio	Control condition
0 %	• Ignition switched off • Engine stopped • Engine start (cranking)
0―100 % (Duty ratio determined by measuring the element temperature by the A/F sensor heater element impedance)	• After engine warm-up (such as value fluctuates by battery condition)