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:

Shift Solenoid No.1 [Fw6 A EL, Fw6 Ax EL]
Purpose/Function Shift solenoid No.1 adjusts the hydraulic pressure in the low clutch circuit based on the current demand from the TCM according to the vehicle conditions. Construction Shift solenoid No.1 is installed to the solenoid control valve body. Shift solenoid ...

Wheel Hub Component Inspection
Wheel Bearing Excessive Play Inspection 1. Install the magnetic base and dial gauge as shown in the figure and measure the wheel bearing axial excessive play. If it exceeds the maximum specification, replace the wheel hub component. Rear wheel bearing maximum play ...

Camshaft Position (CMP) Sensor
Purpose/Function Detects the camshaft speed as basic information for mainly determining the fuel injection timing and ignition timing. Detects the camshaft speed and inputs it to the PCM as a CMP signal. Construction Intake CMP sensor Installed on the cylinder head. ...