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:

Cruise Control Switch Inspection
1. Disconnect the negative battery cable and wait for 1 min or more.. 2. Remove the driver?side air bag module.. 3. Disconnect the clock spring connector (part wiring harness-side). 4. Measure the resistance between clock spring terminals E and A (part wiring harness-side) using a tester. ...

Windshield Removal
1. Disconnect the negative battery cable.. 2. Remove the following parts: a. Windshield wiper arm and blade. b. Cowl grille. c. Rain sensor (with auto light/wiper system). d. Auto-dimming mirror (with auto-dimming mirror). e. Rearview mirror (without auto-dimming mirror). f. A-pillar t ...

Car Navigation Unit Removal/Installation
CAUTION: The audio unit communicates with the car-navigation unit and records the presence/non-presence of the car-navigation unit when the ignition is switched to ACC or ON (engine off or on) after connecting the negative battery cable. If the commander switch is installed ...