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:

Heater Core Inspection
1. Inspect the heater core for damage, cracks, and water leakage. If there is any malfunction, replace the heater core. 2. Visually inspect the fins for bending. If there is any bending, use the end of a flathead screwdriver to straighten the fins. 3. Visually inspect ...

Headlight Bulb Removal/Installation
Halogen Type Headlight LO bulb 1. Disconnect the negative battery cable.. 2. Disconnect the connector. 3. Rotate the headlight LO bulb in the direction of the arrow (1) shown in the figure to remove it in the direction of the arrow (2) shown in the figure. CAUTION: A halogen bu ...

Shroud Side Member Installation [Panel Replacement]
Symbol Mark Installation Procedure 1. When installing new parts, measure and adjust the body as necessary to conform with standard dimensions. 2. Drill holes for the plug welding before installing the new parts. 3. After temporarily installing new parts, make sure the related parts fit p ...