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.
2017 Mazda 5 GS, Automatic TransFACTORY OEM SERVICE PROCEDURE
Fuel Injector Operation Inspection
If simulation function of M-MDS is used:
FUEL INJECTOR OPERATION INSPECTION PROCEDURE
| STEP | INSPECTION | RESULTS | ACTION |
|---|---|---|---|
| 1 | Start the engine and warm it up until normal operating temperature. Access the INJ_1, INJ_2, INJ_3 and INJ_4 PIDs using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST .) Turn the fuel injector from on to off using the PIDs each cylinder. Does the engine speed drop? |
Yes | Fuel injector work properly. |
| No | Go to the next step. | ||
| 2 | Disconnect the fuel injector that the engine speed does not drop at Step 1. Inspect open or short circuit between suspect fuel injector terminal B (wiring harness-side) and fuel pump relay terminal C (wiring harness-side). Is there any malfunction? |
Yes | Repair or replace the wiring harness for a possible open or short circuit. |
| No | Go to the next step. | ||
| 3 | Inspect for open or short circuit between the following terminals (wiring harness-side):
Is there any malfunction? |
Yes | Repair or replace the wiring harness for a possible open or short circuit. |
| No | Go to the next step. | ||
| 4 | Inspect the suspected fuel injector. (See FUEL INJECTOR INSPECTION .) Is there any malfunction? |
Yes | Replace the suspected fuel injector. (See FUEL INJECTOR REMOVAL/INSTALLATION .) |
| No | Replace the PCM. (See PCM REMOVAL/INSTALLATION .) |
If simulation function of M-MDS is not used:
FUEL INJECTOR OPERATION INSPECTION PROCEDURE
| STEP | INSPECTION | RESULTS | ACTION |
|---|---|---|---|
| 1 | While cranking the engine, inspect for fuel injector operation sound at each cylinder using a soundscope. Is the operation sound heard? |
Yes | Fuel injector work properly. |
| No | Go to the next step. | ||
| 2 | Disconnect the fuel injector that the operation sound is not heard. Inspect open or short circuit between suspect fuel injector terminal B (wiring harness-side) and fuel pump relay terminal C (wiring harness-side). Is there any malfunction? |
Yes | Repair or replace the wiring harness for a possible open or short circuit. |
| No | Go to the next step. | ||
| 3 | Inspect for open or short circuit between the following terminals (wiring harness-side):
Is there any malfunction? |
Yes | Repair or replace the wiring harness for a possible open or short circuit. |
| No | Go to the next step. | ||
| 4 | Inspect the suspected fuel injector. (See FUEL INJECTOR INSPECTION .) Is there any malfunction? |
Yes | Replace the suspected fuel injector. (See FUEL INJECTOR REMOVAL/INSTALLATION .) |
| 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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