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P2DA1: Gear Shift Control Module B Supply Voltage Low

Supply voltage on the gear shift control module B is below the expected window.

Medium severity. Can I keep driving?It depends on the symptoms. If the car is running normally you can go to a repair shop; if it goes into limp mode, drive as little as possible.

This code points to an internal problem in the control module or in the circuits that power its sensors. The cause is often voltage or wiring, not the unit itself.

Symptoms

  • Check engine or transmission warning light on
  • Harsh, delayed, or missing shifts
  • Possible limp mode (locked in one gear)
  • Slipping or shuddering during gear changes

Most likely causes

  • Module supply fuse blown
  • Wiring fault

What to check, in order

Start with the simplest. You can tick off each step.

Good to know

  • Repair difficulty: medium
  • It can trigger limp mode.

What each character of P2DA1 means

  • P: Powertrain: engine and transmission
  • 2: Generic code: same on every make
  • D: Subsystem depends on the code range
  • A1: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2DA1?

It depends on the symptoms. If the car is running normally you can go to a repair shop; if it goes into limp mode, drive as little as possible.

What causes code P2DA1?

The most common causes are: module supply fuse blown; wiring fault.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.