Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

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Component Testing









1. Warm up the engine and check that engine coolant temperature is 80-90°C (176-194°F).
2. Disconnect the oxygen sensor and connect the digital voltmeter.

Caution: Do not pull the connector and lead wires strongly when disconnecting the oxygen sensor connector.

3. While repeatedly racing the engine, measure the output voltage of the oxygen sensor.
4. Replace the oxygen sensor if it is faulty.