P2784Input/Turbine Speed Sensor A/B Correlation
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- 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.
- What you may notice
- Harsh or erratic shifts
- Emergency mode with fixed gear
- MIL on
- Likely causes
- LikelyMetal debris on a magnetic speed sensor tip
- PossibleOne sensor giving a weak or distorted signal
- RareDamaged tone wheel or excessive air gap
- RareSignal interference from poor shielding or connectors
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.