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C1555moderate severity✨ AI-generated

Power Supply Voltage Fault

The control module detects a voltage problem in its power supply.

Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.

What it means (plain English)

Basically, the computer isn't getting the right amount of power it needs to work properly. It should see around 12-14 volts when the engine is running.

What the computer is actually seeing

The control module monitors the voltage level at its power supply input. If this voltage drops below 10 volts or exceeds 16 volts during operation, it sets this code.

What a healthy reading looks like

12-14 volts is normal. Below 10 volts or above 16 volts triggers the fault.

Guided diagnostic — the DiagCoach way

Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.

  1. 1Check battery voltage with a multimeter; should be between 12-14 volts when running. If not, charge or replace the battery. Decision: Is voltage normal? Yes - proceed. No - fix electrical issue.
  2. 2Inspect all wiring and connectors leading to the control module. Look for signs of wear or corrosion. Decision: Are all connections secure and undamaged? Yes - proceed. No - repair or replace damaged wiring/connector.
  3. 3Check the ground connection for the control module; it should have a clean and tight connection. Decision: Is the ground connection good? Yes - proceed. No - improve ground connection.
  4. 4If all previous checks are good, consider testing the control module with a scan tool or replacing it.
  5. 5Clear the code and see if it returns after performing the checks.

Common causes

  • Bad battery connections
  • Wiring issues (frayed, corroded, or shorted wires)
  • Faulty control module
  • Bad ground connection
  • Issues with the vehicle's electrical system

Typical repair cost

$$-$$$

Related codes

Frequently asked questions

Is it safe to drive with this code?

It's best to fix this soon. You may experience electrical issues or intermittent failures.

Will this code come back after clearing?

If the underlying issue isn't fixed, it will likely return.

Why does this code appear after a jump start?

A jump start can cause voltage spikes; if your battery or connections are weak, it might trigger this code.

Working a real vehicle right now?

Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.

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