Start the engine and run it at idle.
Connect WDS or equivalent to the DLC-2.
Verify that P0506, P0507, or P0511 is not displayed. If P0506, P0507 or P0511 are displayed, perform DTC inspection. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .

NOTE: Excludes temporary idle speed drop just after the loads are turned on.

Select RPM PID.
Verify engine speed is within specification under each load condition. See ENGINE SPEED SPECIFICATIONS table. If load condition is not as specified, inspect following:
- A/C switch and related harness. Refer to appropriate MANUAL A/C-HEATER SYSTEMS or AUTOMATIC A/C HEATER SYSTEMS articles in AIR CONDITIONING & HEATING.
- Fan switch and related harness. Refer to appropriate MANUAL A/C-HEATER SYSTEMS or AUTOMATIC A/C HEATER SYSTEMS articles in AIR CONDITIONING & HEATING.
- Power Steering Pressure (PSP) switch and related harness. Refer to POWER STEERING PRESSURE SWITCH under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - MAZDA6, MIATA, MPV, PROTEGE & PROTEGE5 article.

ENGINE SPEED SPECIFICATIONS

Load Condition

⁽¹⁾ Engine Speed (RPM)

No Load

600-700

E/L Operating

650-750

P/S Operating

650-750

A/C Operating ⁽²⁾

Refrigerant Pressure Low ⁽³⁾

700-800

Refrigerant Pressure High ⁽⁴⁾

700-800

⁽¹⁾	Neutral or Park position.

⁽²⁾	A/C switch and fan switch are on.

⁽³⁾	Refrigerant pressure switch (middle pressure) is off.

⁽⁴⁾	Refrigerant pressure switch (middle pressure) is on.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Load Compensation Inspection