P2620: Throttle Position Output Circuit Open
What to do
The engine will respond to the accelerator exactly as normal. The problem shows up in the gearbox: changes at the wrong moments, hunting between gears, and most obviously kickdown that no longer works — flooring the pedal gives you a responsive engine and no downshift.
That combination is the important thing to report, because it points away from the transmission itself. The engine module knows exactly where the throttle is — it is proving that every time you accelerate — and the fault is that the message is not reaching the transmission module. A transmission that is stripped, rebuilt or replaced on the strength of this will behave identically afterwards. Ask for the wiring between the two modules to be checked, and for the transmission module's own view of throttle position to be compared with the engine module's on a scan tool. That takes minutes and settles it.
What this code means
An open circuit on the output by which the engine module passes throttle position to another module.
The same inversion as the rest of this family — this is a signal being sent, not read — and the same exoneration follows: the throttle position sensor, the throttle body and the accelerator pedal are all working, because the module had a value to pass on.
What receives it is almost always the transmission, and that makes the symptom specific and recognisable. An automatic transmission decides when to change gear largely from how far the throttle is open and how quickly it moved: a light throttle asks for an early, gentle upshift; a sudden wide opening asks for a downshift and a hard hold. Take that information away and the transmission is left guessing.
So the presenting complaint is a gearbox one, and it is worth recognising because it gets gearboxes stripped. Shifts happen at the wrong points, the transmission hunts between gears, and — the clearest single sign — kickdown stops working: flooring the pedal produces a willing engine and no downshift, because the module that would have ordered the downshift never learned the pedal moved.
The cheapest thing anyone can do with this code is notice that the engine responds perfectly to the throttle while the transmission behaves as though it does not. That gap is the diagnosis.
Likely causes
Start here
- Open circuit in sensor wiring · moderate
- Corroded or loose connector · easy
- Damaged wiring harness · moderate
Less common
- Faulty receiving module input · specialist
- Faulty transmission control module · specialist
Rare
- Faulty engine control module · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
Sign in or create an account to add what you found about P2620.