Input/Turbine Speed Sensor "A"/"B" Correlation
The P2784 code means the vehicle's onboard diagnostic system has detected: Input/Turbine Speed Sensor "A"/"B" Correlation. This is a moderate severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- moderate
- Estimated cost
- $100 - $500 (usually one of the two disagreeing sensors, or wiring between them)
Read and clear transmission codes. Many trans codes are caused by low or burnt fluid -- check level and color before assuming the worst.
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Common Symptoms
- Check Engine Light on
- Drivability may be normal - many circuit faults show no symptom the driver notices
- The affected system may fall back to a default strategy, costing power or economy
- Related values implausible or frozen on a scan tool
Probable Causes (Ranked by Likelihood)
- Fault in the Input/Turbine Speed Sensor "A"/"B" Correlation circuit: a fault in this circuit High
- Damaged wiring, a chafed harness, or a corroded connector at the Input/Turbine Speed Sensor "A"/"B" Correlation High
- Failed Input/Turbine Speed Sensor "A"/"B" Correlation Moderate
- Control module input/driver fault (rule this out last - it is the least common) Low
Frequently Asked Questions
What does P2784 mean?
P2784 is a generic OBD-II code defined by SAE J2012 as "Input/Turbine Speed Sensor "A"/"B" Correlation". It means the control module detected a fault in this circuit
Can I keep driving with P2784?
Yes for normal use, but get it diagnosed - the system is running on a fallback strategy and a small wiring fault left alone tends to become a bigger one.
Does P2784 mean the same thing on every car?
Yes. P2784 is in the generic (SAE J2012) range, so the definition is standardized across manufacturers. The specific component location and repair procedure still vary by vehicle - check your service information.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
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Read the code and freeze-frame data, then watch the Input/Turbine Speed Sensor "A"/"B" Correlation live on a scan tool.
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Inspect the connector and harness at the Input/Turbine Speed Sensor "A"/"B" Correlation before replacing anything - wiring and corrosion cause most of these.
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Back-probe the circuit and compare signal, ground, and reference voltage against the service-manual values.
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Wiggle-test the harness while watching the live value if the fault is intermittent.
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Clear the code and confirm with a road test that covers the conditions in the freeze frame.
Sources 1
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
Commonly Affected Vehicles
- All OBD-II vehicles - this is a generic (SAE J2012) code with the same meaning across makes
Related Codes
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