PID 4C%

Commanded throttle actuator

How far the unit ASKS the throttle to open. This is a command, not a fact: what actually happened is shown by PID 11, and PID 47 is the second throttle where one exists. On a healthy car the command and the position track each other closely. If the command rises while the position lags or jitters, the throttle is sticking — usually from carbon around its edge.

What is normal

Compare it with the actual position: a noticeable gap means the throttle is not following the command.

These figures hold for most cars, but the maker has the last word: some engines run hotter or idle higher by design.

Codes about this parameter

P0121Throttle position sensor A circuit range/performance P0122Throttle position sensor A circuit low input P0123Throttle position sensor A circuit high input

Codes behind this reading

If the value is out of range, the unit usually says so with one of these codes.

P2100Throttle actuator — circuit open P2101Throttle actuator — range or performance fault

How it feels behind the wheel

The same fault shows itself in different ways. Each sign below says what to look at in the live data.

The revs are capped and the car will not accelerateThe pedal is flat to the floor but the engine caps out around three thousand and goes no further. The car moves, but sluggishly, and overtaking is impossible. The check light is often on.The car has lost powerThe car moves, but sluggishly: flooring the throttle changes nothing, the revs climb reluctantly. Often the lamp is on as well.

How to see it

In CarScan: the Live data tab, «Start polling». The app asks the car several times per second, draws a graph and remembers the highest and lowest value of the trip.

What the app does