P00FD

Symptoms

• Check Engine Light or Battery Management System Warning Light
• Unstable operation of the start-stop system
• Auxiliary Battery Low Warning
• Possible problems with electrical consumers (lighting, media system)
• On hybrids - reduced recovery efficiency and fuel consumption

Causes

• Aging and degradation of optional battery B
• Auxiliary battery charging system malfunction
• Current leakage leading to constant battery discharge
• Battery B current sensor (IBS) fault
• Poor contact in the auxiliary battery charging circuit

How to Fix

1. Read battery management system codes and data via diagnostic scanner
2. Check the voltage of battery B at rest (normal 12.4–12.8V) and under load
3. Perform a load test on battery B to check its actual condition
4. Check battery B charging current with engine running/charging
5. Measure the leakage current with the car turned off (the norm is less than 50 mA)
6. If the battery degrades, replace it; If there is a problem with charging, diagnose the power management system

Related codes

Error P00FD by Vehicle Brand