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P2550 — Torque Management Request Input Signal B Low

Manufacturer-specificPowertrain (engine & transmission)

P2550 indicates that the Torque Management Request Input Signal B circuit is reading a voltage lower than expected. This signal is used by the powertrain control module (PCM) to gauge driver torque demand via the accelerator pedal position (APP) sensor. When the signal is low, the PCM may limit engine torque or trigger a reduced‑power mode.

Symptoms

What causes it — most likely first

1. Faulty accelerator pedal position (APP) sensor or its signal B circuit

The APP sensor may output a voltage below the specified range due to internal failure, causing the PCM to see a low torque request signal.

2. Wiring harness short to ground or open circuit in the signal B line

Damaged chafed wires, corroded terminals, or a broken wire can pull the signal low or interrupt it entirely.

3. Loose or corroded connector at the APP sensor or PCM

Poor contact increases resistance and can pull the signal voltage down, especially under vibration or temperature changes.

4. Faulty throttle position sensor (TPS) if integrated with APP

In some designs the TPS shares the torque request circuit; a failing TPS can drag the signal low.

5. PCM input circuit failure (rare)

The PCM’s internal input driver for signal B could be defective, but this is uncommon and should be considered only after sensor and wiring checks.

How it's diagnosed

  1. Scan the vehicle for codes and note freeze‑frame data to confirm P2550 and any related codes.
  2. Visually inspect the accelerator pedal position sensor, its connector, and the wiring harness for signs of damage, corrosion, or loose connections.
  3. Measure the APP sensor signal B voltage with a multimeter or scan tool while slowly depressing the pedal; compare to manufacturer specifications.
  4. Test for continuity and short‑to‑ground on the signal B wire between the sensor and PCM; repair any faults found.
  5. If sensor and wiring are within spec, monitor live data for signal stability; if the PCM still reads low, consider a PCM input test or replacement as a last resort.

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationManufacturer-specific (P1/B1/C1/U1)
Related codesP2548 — Torque Management Request Input SignalP2549 — Torque Management Request Input SignalP2551 — Torque Management Request Input SignalP2553 — Throttlefuel Inhibit Circuit RangeperfP2554 — Throttlefuel Inhibit Circuit LowP2555 — Throttlefuel Inhibit Circuit High

Frequently asked

Is replacing the PCM a common fix for P2550?

No. The PCM is rarely the cause; most cases stem from the accelerator pedal position sensor, its wiring, or connectors. PCM replacement should only be considered after those components have been verified good.

Can a dirty throttle body cause this code?

A dirty throttle body does not directly affect the torque request input signal; however, if the throttle position sensor is faulty and shares the circuit, it could contribute. Cleaning the throttle body alone will not resolve a low signal B condition.

Will clearing the code fix the problem?

Clearing the code only turns off the Check Engine Light temporarily. If the underlying fault remains, the code will return once the PCM detects the low signal again.