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.
Component Function Check
- PERFORM COMPONENT FUNCTION CHECK
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.
- Check the voltage between ECM harness connector terminals under the following conditions.
DTC
ECM
Condition
Voltage
+
-
Connector
Terminal
Connector
Terminal
P0420
F117
84
[HO2S2 (bank 1)]
F116
43
Keeping engine speed at 2, 500 RPM constant under no load
The voltage fluctuation cycle takes more than 5 seconds.
- 1 cycle: 0.6 - 1.0 -> 0 - 0.3 -> 0.6 - 1.0
P0430
77
[HO2S2 (bank 2)]
Is the inspection result normal?
YES
INSPECTION END
NO
Proceed to Diagnosis Procedure .
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.