BULLETIN NOTES
This SA supersedes the previously issued SA(s) listed below. The changes are noted in Red.
Previous SA:

Date(s) Issued:

SA-084/23

12/22/23

APPLICABLE MODEL(S)/VINS
2024 CX-90 PHEV

DESCRIPTION
Some customers with a PHEV CX-90 may report a warning light or a reported issue of A/C malfunction. Upon inspection,
the technician will discover that the vehicle has the P0531 diagnostic trouble code set.
Behavior after P0531:00 is detected
NOTE:
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A minimum of 3 hours after ignition is switched OFF before the next ignition ON is required for one drive cycle.
Pre-A/C should not be used during this time.
To turn off the CHECK ENGINE light without using MDARS (so that customer does not need to come into the
dealer), perform 3 drive cycles with a minimum of 3 hours between each one (9 hours total).
If the outside temperature is below 14°F (-10°C), the fault determination logic is not activated and the normal
determination is not counted up, therefore the CHECK ENGINE light remains ON.

1. Operation when DTC is detected
• P0531:00 is stored in the PCM.
• CHECK ENGINE light is ON.
• No A/C operation (as fail-safe).
2. After Ignition is switched OFF/ON
• P0531:00 moves into Past history.
• CHECK ENGINE light stays ON continuously.
• A/C can operate normally (no fail-safe), remote/timer climate control is also available.

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3. After 3 drive cycles to determine normality
• P0531:00-PCM is stored in Past.history.
• CHECK ENGINE light goes OFF.
• A/C operates normally.
Logic to operate pre-A/C system:
• Pre-A/C operation is described in the Connected Vehicle OM.
• The CX-90 PHEV pre-A/C function will not operate when the high voltage battery State of Charge (SOC) is low.
Start permission condition: Meter SOC is 3.5% or higher.
Stop condition: Stops when meter SOC reaches 0%.
• In case of timer setting, departure time must be at least 30 minutes after the current time (e.g., setting departure
time 15:20 at time 15:00 is not acceptable).
• Pre-air conditioner does not work when a door is open.
• When the outside air temperature is low, the PTC water heater will operate alone and the electric A/C compressor
will not run.
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REPAIR PROCEDURE
1. Verify the customer's concern.
2. Use MDARS to check for DTCs.
Is P0531 the only DTC set?
• YES - Continue to STEP 3.
• NO - Follow the WSM to diagnose and repair the vehicle.
3. Follow the appropriate WSM procedure for P0531 to confirm there isn't an electrical or mechanical fault.
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P0531:00 [PCM (e-SKYACTIV PHEV)]

NOTE: After a few hours without using the A/C, the readings from the three A/C pressure sensors should nearly align if
the sensors and wiring are OK.

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If your test results do not find any fault, do not replace any parts. The customer's concern may be software
related and this is under investigation.

4. Clear all DTC and test drive the vehicle using the A/C or defrost function to confirm no DTC sets again.
• If no DTC is set, release the vehicle back to the customer and explain to them the following:
a. This issue is triggered by using the timed and remote heat/cooling functions and is under investigation.
b. Until a solution is developed, turn off any timed heating/cooling functions in your vehicle and refrain from
using the MyMazda app to remotely heat or cool your vehicle.
5. Verify any repairs.

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