Powertrain, generic (extended)

P2784 Input/Turbine Speed Sensor A/B Correlation

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P2784 belongs to transmissions with two input or turbine speed sensors whose readings can be compared. When both are healthy their values agree, or differ only by a known ratio; P2784 is set when they drift apart for longer than the module tolerates while each circuit on its own looks fine. No manufacturer documents P2784 publicly, so it stays open which sensor pairs are compared in practice. The individual circuits have their own codes: P0715 family for sensor A and P2765 to P2768 for sensor B. Mitsubishi's 2019 CVT shows how sensor B can be the turbine sensor, diagnosed when it reads below 150 rpm for 5 s while the primary pulley turns faster than 500 rpm. Metal debris on a magnetic tip, a loose sensor or a damaged tone wheel are typical causes.

Likely causes

Metal debris on a magnetic speed sensor tip
One sensor giving a weak or distorted signal
Damaged tone wheel or excessive air gap
Signal interference from poor shielding or connectors

Symptoms

  • Harsh or erratic shifts
  • Emergency mode with fixed gear
  • MIL on

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–1,500
Time0.5–6 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

input shaft speed sensor ainput shaft speed sensor btone wheel

Related codes

P0715P0716P2765P2766P2767

References: mitsubishitechinfo.com, law.cornell.edu.