System Voltage Malfunction

What it means

The engine computer has detected that its supply voltage is outside the expected range or implausible. The cause is usually the battery, the alternator, or the terminals and ground connections, and it can affect sensors and electronic systems.

Related codes: P0561P0562P0563P0620

Symptoms4

• Battery light or check engine light on.
• Weak engine cranking or slow starter.
• Dim or flickering lights.
• Odd behavior from electrical devices or several codes in different modules.

Possible causes6

• Weak or failed battery.
• Corroded or loose battery terminals.
• Faulty alternator or its voltage regulator.
• Loose or damaged alternator belt.
• Poor ground connections between the engine and body.
• Faulty fuse or relay feeding the computer.

How to diagnose5

1. Measure battery voltage with the engine off and running, and compare with the manufacturer specification.
2. Test the battery with a load tester.
3. Inspect terminals, cables and ground points for corrosion or looseness.
4. Compare system voltage on the scan tool with voltage measured at the battery; a large difference points to resistance in the connections.
5. Inspect the alternator belt and its tension.

How to fix5

1. Clean the battery terminals and tighten them.
2. Repair or clean the ground points.
3. Charge the battery, or replace it if it fails the load test.
4. Replace the alternator belt or the alternator if charging is incorrect.
5. Clear the codes and confirm steady voltage while running with electrical loads on.

Repair cost

In Saudi riyals; the highlighted part is the expected range for this fault.

The cost is low for cleaning terminals or fixing a ground, and rises when the battery or alternator must be replaced.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions