Mazda CX-5 Service & Repair Manual: Air Fuel Ratio (A/F) Sensor Heater Control

Mazda CX-5 Service & Repair Manual / Engine / Control / Air Fuel Ratio (A/F) Sensor Heater Control

Outline

Based on the control of the A/F sensor heater, a stabilized oxygen concentration is detected even at low exhaust temperatures, and feedback control of fuel injection even at cold engine start is made possible for improved cold temperature exhaust emission performance.
Both emission performance and sensor protection have been improved by duty control of the heater according to engine operation conditions (exhaust gas temperature).
A pre-heater 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

Operation

Pre-heater 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 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 (value fluctuates by battery condition, etc.)

Output duty ratio

Control condition

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 (value fluctuates by battery condition, etc.)

Accelerator Pedal Position (App) Sensor

Purpose/Function Detects the accelerator pedal depression amount as basic information for mainly determining the throttle valve opening. Detects the accelerator pedal depression amou ...

Air Fuel Ratio (A/F) Sensor Inspection

A/F Sensor Inspection 1. Connect the M-MDS to the DLC?2. 2. Switch the ignition ON (engine on). 3. Warm up the engine to normal operating temperature. 4. Access the following PIDs using the M-M ...

Other materials:

Transfer Oil Inspection [Fw6 Ax EL]
1. Park the vehicle on level ground. 2. Remove the oil level plug with the washer. 3. Checking by hand, verify that the oil is near the brim of the plug hole. If the oil level is low, add the specified amount and type of oil through the oil level plug hole. Transfer oil ...

Evaporator
Purpose The evaporator cools the passing air. Function The evaporator vaporizes the atomized refrigerant flowing internally, and the air passing through the evaporator is cooled by the release of latent heat. The moisture in the air is condensed at this time and dehumidifie ...

Air Intake Actuator Inspection [Manual Air Conditioner]
1. Connect battery positive voltage to air intake actuator terminal B (or C), connect terminal C (or B) to ground, and then verify that the air intake actuator operates as shown in the table. If the operation condition is not normal, replace the air intake actuator. ...