Toyota Corolla (E120): System too lean/rich

Dtc p0171 system too lean (bank 1)

Dtc p0172 system too rich (bank 1)

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Monitor description
While the engine is being cranked, the battery positive voltage is applied to terminal sta of the ecm. If the ecm detects the starter control signal (sta) while the vehicle is driving, it will conclude that there is a fault in the starter control circuit. The ecm will turn on the mil and a d ...

Inspection procedure
Hint: if dtcs besides misfire are memorized simultaneously, first perform the troubleshooting for them. Read freeze frame data using the hand-held tester or the obd ii scan tool. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, it ...

Definition of terms
Term Definition Monitor description Description of what the ecm monitors and how it detects malfunction (monitoring purpose and its details). Related dtcs Diagnostic code Typical enabling condition Preconditions that allow the ecm to detect m ...