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.

2020 Subaru Ascent BaseFACTORY OEM SERVICE PROCEDURE

Diagnostics with Phenomenon: List

NOTE: Malfunction of parts other than those listed is also possible. Ref. to MECHANICAL (H4DOTC)>SYMPTOMS AND CAUSES .

Item		Reference
Engine does not start NOTE: Perform the diagnosis in the numerical order on the right.	1. Check fuel level	Check the fuel level.
	2. Check immobilizer	With Telematics: Ref. to TELEMATICS SYSTEM (DIAGNOSTICS)>DIAGNOSTICS WITH PHENOMENON>INSPECTION>ENGINE WILL NOT START .
		Without Keyless Access with Push Button Start: Ref. to IMMOBILIZER (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .
		With Keyless Access with Push Button Start: Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .
	3. Check ECM power supply and ground line	Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>DIAGNOSTICS WITH PHENOMENON>CHECK POWER SUPPLY AND GROUND LINE OF ENGINE CONTROL MODULE (ECM) .
	4. Inspection of starter motor circuit	Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>DIAGNOSTICS WITH PHENOMENON>STARTER MOTOR CIRCUIT .
	5. Inspection of ignition control system	Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>DIAGNOSTICS WITH PHENOMENON>IGNITION CONTROL SYSTEM .
	6. Inspection of fuel pump circuit	Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>DIAGNOSTICS WITH PHENOMENON>FUEL PUMP CIRCUIT .
	7. Inspection of fuel injector circuit	Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>DIAGNOSTICS WITH PHENOMENON>FUEL INJECTOR CIRCUIT .
Brake override does not operate	Check brake override system	Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>DIAGNOSTICS WITH PHENOMENON>CHECK BRAKE OVERRIDE SYSTEM .

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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