CarScan
PID 4A%

Accelerator pedal position E

The second accelerator pedal position sensor. A pair to PID 49: two sensors on one pedal are there not for precision but for cross-checking — the unit trusts the pedal only while both say the same thing. On a graph their lines should run side by side from idle to full travel. A step or a gap over part of the travel means the sensor track is worn exactly there.

What is normal

Compare it with the first: a disagreement is the pedal fault itself, even if the pedal feels normal.

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

Codes behind this reading

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

P2127Accelerator pedal sensor E — low signalP2128Accelerator pedal sensor E — high signal

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.Cruise control stopped engagingThe button clicks but cruise never takes the speed — or it drops out after a few seconds.

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