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

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HO2S Heater

Heated oxygen sensors are used in order to minimize the amount of time required for a closed loop fuel control operation and in order to allow accurate catalyst monitoring. The oxygen sensor heater greatly decreases the amount of time required for fuel control sensors Bank 1 HO2S 1 and Bank 2 HO2S 1 to become active. The oxygen sensor heaters are required by catalyst monitor sensors Bank 1 HO2S 2 and Bank 1 HO2S 3 to maintain a sufficiently high temperature which allows accurate exhaust oxygen content readings further from the engine.