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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Computerized Engine Controls (CEC)


Many components of the emission control system are monitored for proper operation by the Electronic Control Unit or ECU. In the event improper operation is detected the ECU will store an error code or codes indicating which component has failed to operate correctly. These codes can be extracted to assist in diagnosis and testing of emission control system failures. Be sure to extract diagnostic codes before disconnecting the vehicle battery or the codes will be lost. (The diagnostic codes will not be lost if battery power is restored to the ECU in less than ten seconds.)