P0639
Throttle Actuator Control Range/Performance (Bank 2)
- Severity
- Critical
- Driving
- Drive only to a garage
The throttle actuator on bank 2 is not reaching the position the module commanded. The circuit is not being blamed - the throttle plate is physically not going where it was told, usually because carbon has made it stiff. The module responds by dropping the engine into a reduced-power mode, and that happens without warning.
Possible causes
- CommonCarbon build-up making the throttle plate stiff
- CommonFailing throttle actuator motor
- CommonThrottle body never relearned after cleaning or replacement
- PossibleFaulty throttle position sensor giving an inaccurate reading
- PossibleHigh resistance in the wiring weakening the drive
- PossibleVacuum leak downstream affecting the airflow the module expects
What you might notice
- Sudden loss of power - reduced-power mode
- Engine will not rev beyond a low limit
- Rough or unstable idle
- Warning light for reduced engine power
- Hesitation
What to check, in order
- Be aware that power can be cut without warning. Avoid overtaking and motorway slip roads until this is fixed.
- Compare commanded against actual throttle position on the live data screen through a full sweep.
- Inspect the throttle body for carbon. On a drive-by-wire throttle, cleaning without running the relearn procedure afterwards can leave the idle worse than before - check whether a relearn is specified before starting.
- Check the wiring for high resistance before replacing the actuator.
- Read all codes - throttle position sensor codes alongside this one change the diagnosis.
Read this code from your own car
Plug an ELM327 adapter into the OBD-II port under the dashboard. Pin16 reads every stored, pending and permanent code, explains each one like this page does — offline, with no account — and shows what the car recorded when the fault was set.
Where this code sits
P00xxP01xxP02xxP03xxP04xxP05xxP06xxP07xxP08xxP09xxP0AxxP0BxxP0CxxP0DxxP0ExxP0FxxP10xxP11xxP12xxP13xxP14xxP15xxP16xxP17xxP18xxP19xxP1AxxP1BxxP1CxxP1DxxP1ExxP1FxxP20xxP21xxP22xxP23xxP24xxP25xxP26xxP27xxP28xxP29xxP2AxxP2BxxP2CxxP2DxxP2ExxP2FxxP30xxP31xxP32xxP33xxP34xxP35xxP36xxP37xxP38xxP39xxP3AxxP3BxxP3CxxP3DxxP3ExxP3Fxx
Computer output circuits and control module
P0600P0601P0602P0603P0604P0605P0606P0607P0608P0609P0610P0611P0612P0613P0614P0615P0616P0617P0618P0619P0620P0621P0622P0623P0624P0625P0626P0627P0628P0629P0630P0631P0632P0633P0634P0635P0636P0637P0638P0639P0640P0641P0642P0643P0644P0645P0646P0647P0648P0649P0650P0651P0652P0653P0654P0655P0656P0657P0658P0659P0660P0661P0662P0663P0664P0665P0666P0667P0668P0669P0670P0671P0672P0673P0674P0675P0676P0677P0678P0679P0680P0681P0682P0683P0684P0685P0686P0687P0688P0689P0690P0691P0692P0693P0694P0695P0696P0697P0698P0699