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.
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HOMESERVICE MANUALSNISSAN-DATSUN2004ALTIMA S, AUTOMATICREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCEENGINE CONTROL SYSTEM - 2.5LDTC P0420: THREE WAY CATALYST FUNCTIONOVERALL FUNCTION CHECKWITH GST
2004 Nissan-Datsun Altima S, Automatic
With GST
2004 Nissan-Datsun Altima S, AutomaticSECTION With GST
- Start engine and warm it up to the normal operating temperature.
- Turn ignition switch OFF and wait at least 10 seconds.
- Start engine and keep the engine speed between 3, 500 and 4, 000 RPM for at least 1 minute under no load.
- Let engine idle for 1 minute.
- Open engine hood.
- Set voltmeter probe between ECM terminal 74 and ground.
- Keep engine speed at 2, 500 RPM constant under no load.
- Make sure that the voltage does not vary for more than 5 seconds.
If the voltage fluctuation cycle takes less than 5 seconds, go to "DIAGNOSTIC PROCEDURE ".
- 1 cycle: 0.6 - 1.0 V --> 0 - 0.3 V --> 0.6 - 1.0 V
RENDER: 1.0x
NO RELATED
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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.