What Does P2551 Mean?
The PCM has detected an abnormally high voltage or signal on the Torque Management Request Input Signal B circuit. This indicates a potential short to voltage or communication fault with systems that request engine torque management.
Common Causes
35%
Short to voltage (battery or 5V reference) in signal B wiring harness
25%
Faulty transmission control module or traction control module output driver
20%
Corroded or damaged PCM connector causing high resistance or cross-circuit short
15%
Internal PCM failure in torque request input circuit
5%
Failed voltage regulator in requesting control module
Diagnostic Steps
1
Step 1: Measure voltage on torque management input signal B at PCM connector; abnormally high reading (>5V) confirms code
2
Step 2: Disconnect requesting module (TCM/traction control) and retest voltage to isolate source of high signal
3
Step 3: Inspect wiring harness for damage, particularly near hot components or sharp edges causing short to power
4
Step 4: Test requesting module output driver function with manufacturer scan tool or oscilloscope
5
Step 5: Check PCM connector terminals for spread pins, corrosion, or cross-contamination between adjacent circuits
Estimated Repair Cost
$150 - $900
Parts + labor, varies by vehicle and location
The PCM has detected an abnormally high voltage or signal on the Torque Management Request Input Signal B circuit. This indicates a potential short to voltage or communication fault with systems that request engine torque management.
The most common cause of P2551 (Torque Management Request Input Signal "B" High) is: Short to voltage (battery or 5V reference) in signal B wiring harness
Typical repair costs for P2551 range from $150 to $900, depending on the vehicle, location, and whether you do it yourself or go to a shop.
May prevent proper torque reduction during traction events or transmission shifts, potentially causing wheel spin or harsh shifting. Exercise caution in slippery conditions.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P2551 to identify the root cause.
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Quick Info
Category
Powertrain
System
Torque Management/Engine Control
Difficulty
Type
Generic (SAE)
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