Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2021 Mazda CX-3 AWDFACTORY OEM SERVICE PROCEDURE
Fuel Injector Operation Inspection
If simulation function of M-MDS is used:
ENGINE CONTROL SYSTEM OPERATION INSPECTION DIAGNOSTIC PROCEDURE
| STEP | INSPECTION | ACTION | |
|---|---|---|---|
| 1 | Start the engine and warm it up completely. Access the INJ_1, INJ_2, INJ_3 and INJ_4 PIDs using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST .) Turn each fuel injector from on to off using the PIDs for each cylinder. Does the engine speed drop? |
Yes | Fuel injectors work properly. |
| No | Engine speed does not drop an any cylinder:
Engine speed drops on some cylinders:
|
||
| 2 | Perform the Main Relay Operation Inspection. (See MAIN RELAY OPERATION INSPECTION .) Does the main relay work properly? |
Yes | Go to the next step. |
| No | Repair or replace the malfunctioning part according to the inspection results. | ||
| 3 | Inspect the fuel injector of the suspected cylinder. (See FUEL INJECTOR INSPECTION
.) Is there any malfunction? |
Yes | Replace the fuel injector. (See FUEL INJECTOR REMOVAL/INSTALLATION .) |
| No | Inspect the fuel injector power and/or ground systems related wiring harness and connectors for the suspected cylinder.
|
||
| 4 | Perform the KOER self test using the M-MDS. (See KOEO/KOER SELF TEST
.) Are the DTCs P0201:00, P0202:00, P0203:00 and/or P0204:00 present? |
Yes | Go to the appropriate DTC inspection. (See DTC P0201:00
.) (See DTC P0202:00
.) (See DTC P0203:00
.) (See DTC P0204:00 .) |
| No | Go to the next step. | ||
| 5 | Inspect the fuel injector of the suspected cylinder. (See FUEL INJECTOR INSPECTION
.) Is there any malfunction? |
Yes | Replace the fuel injector. (See FUEL INJECTOR REMOVAL/INSTALLATION .) |
| No | Inspect the following for the suspected cylinder:
|
||
If simulation function of M-MDS is not used:
ENGINE CONTROL SYSTEM OPERATION INSPECTION DIAGNOSTIC PROCEDURE
| STEP | INSPECTION | ACTION | |
|---|---|---|---|
| 1 | Perform the KOER self test using the M-MDS. (See KOEO/KOER SELF TEST
.) Are the DTCs P0201:00, P0202:00, P0203:00 and/or P0204:00 present? |
Yes | Go to the appropriate DTC inspection. (See DTC P0201:00
.) (See DTC P0202:00
.) (See DTC P0203:00
.) (See DTC P0204:00 .) |
| No | Go to the next step. | ||
| 2 | Inspect the fuel injector of the suspected cylinder. (See FUEL INJECTOR INSPECTION
.) Is there any malfunction? |
Yes | Replace the fuel injector. (See FUEL INJECTOR REMOVAL/INSTALLATION .) |
| No | Go to the next step. | ||
| 3 | Inspect the following for the suspected cylinder:
Is there any malfunction? |
Yes | Repair or replace the malfunctioning part according to the inspection results. |
| No | Replace the PCM. (See PCM REMOVAL/INSTALLATION .) |
||
Factory Service Tools
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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.
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