Short answer
Cable throttle (a cable runs from the gas pedal to the throttle body): the TPS is usually a separate, replaceable sensor bolted to the end of the throttle shaft. Electronic, drive by wire throttle (no cable, a motor on the throttle body): the position sensors are usually built into the throttle body, so a sensor fault usually means a throttle body, though some applications have sensor-only parts. Check by part number or VIN before you buy.
Side by side
How cable and electronic throttles differ
| Cable throttle | Electronic (drive by wire) | |
|---|---|---|
| How the throttle opens | A cable from the pedal turns the shaft | A motor turns the shaft; the pedal is a sensor |
| Where the TPS is | Separate part on the end of the shaft | Usually inside the throttle body |
| Signals | Typically one signal, three wires | Typically two throttle signals the computer compares |
| Typical codes | P0120 to P0124 | P0120 to P0124, P2135 and related |
| Usual fix for a bad sensor | Replace the sensor | Replace the throttle body, unless a sensor-only part exists |
| Adjustable? | Some older sensors are (slotted holes) | No |
Why electronic throttles use two sensors
When a motor opens the throttle, the computer has to be sure the throttle is where it thinks it is. So the throttle body carries two position signals, and the computer compares them all the time. OBD-Codes.com describes the throttle body as having two embedded sensors and says that when their voltages stop agreeing, P2135 sets. That is also why these systems often drop into a reduced power mode when something is wrong.
Sensor-only parts for electronic throttles
Do not assume you need a whole throttle body. Some aftermarket makers sell direct-fit sensors for certain electronic throttle bodies: an SMP listing describes its sensor as a direct-fit replacement that lets you replace only the sensor rather than the whole throttle body. Whether one exists for your engine comes down to part number lookup.
Which should you buy?
- Identify your throttle type from the cable (above).
- Read the codes. The codes hub explains each one.
- Test before you buy: the sweep test works for cable throttles; electronic ones are easier through live data.
- Look up the part by VIN or old part number, and check whether a sensor-only replacement exists.
- Compare the cost: TPS replacement cost.
Questions people ask
Is the TPS part of the throttle body?
It is mounted on it either way. On cable throttles it is usually a separate part held by screws. On electronic throttles it is usually inside the throttle body housing and sold as part of the assembly.
How do I know if I have drive by wire?
Open the hood and find the throttle body where the intake tube meets the engine. If a cable from the gas pedal connects to a pulley on it, it is a cable throttle. If there is no cable and a motor housing with a larger connector, it is electronic.
Will cleaning the throttle body fix TPS codes?
Not if the sensor or wiring is bad. Carbon on the throttle plate can cause idle problems that look like a bad TPS, and OBD-Codes.com lists a binding plate among P0124 causes, so cleaning can help in that case. Follow your maker’s guidance; some electronic throttle bodies should not be pried open by hand.
What is the accelerator pedal position sensor?
On electronic throttles, a second set of sensors on the gas pedal tells the computer how far you are pressing it. The computer then moves the throttle with a motor and checks the throttle sensors against the pedal. P2135 can come from either side.
Sources
Last reviewed 2026-10-12. General guidance only: specs, procedures and fitment vary by vehicle, so confirm in your service manual and on the listing before you buy or wrench.