Cause
Faulty alternator
The charging source. On many vehicles the warning lamp circuit is also what starts it charging — the excitation current comes from the battery through the bulb — so a blown warning bulb can stop the alternator charging entirely.
A flat battery and a warning light that never illuminates is one fault, not two.
Typically a moderate job.
Some of these codes mean you should stop driving
1 of the 25 codes this can cause indicate a fault where continuing to drive risks damage or is unsafe. Which one you have matters more than the cause does — read the code's own page before deciding.
Codes this can cause (25)
Codes where this is a likely explanation first, rather than merely a possible one.
- P0560 System Voltage Likely for this code Moderate
- P0561 System Voltage Unstable Likely for this code Moderate
- P0562 System Voltage Low Likely for this code Moderate
- P0563 System Voltage High Likely for this code High
- P0620 Generator Control Circuit Likely for this code Moderate
- P0621 Generator Lamp/L Terminal Circuit Likely for this code Moderate
- P0622 Generator Field/F Terminal Circuit Likely for this code Moderate
- P0625 Generator Field/F Terminal Circuit Low Likely for this code Moderate
- P0626 Generator Field/F Terminal Circuit High Likely for this code Moderate
- P065A Generator System Performance Likely for this code High
- P0883 Transmission Control Module Power Input Signal High Likely for this code High
- P2500 Generator Lamp L-Terminal Circuit Low Likely for this code High
- P2501 Generator Lamp L-Terminal Circuit High Likely for this code High
- P2502 Charging System Voltage Likely for this code High
- P2503 Charging System Voltage Low Likely for this code High
- P2504 Charging System Voltage High Likely for this code Stop driving High
- P2508 Engine Control Module Power Input Signal High Likely for this code High
- U3506 Control Module Input Power B Circuit High Likely for this code Moderate
- U350A Control Module Input Power C Circuit High Likely for this code Moderate
- P0880 Transmission Control Module Power Input Signal High
- P0881 Transmission Control Module Power Input Signal Range/Performance High
- P0882 Transmission Control Module Power Input Signal Low High
- P2209 NOx Sensor Heater Sense Circuit Range/Performance Bank 1 Sensor 1 Moderate
- P2222 NOx Sensor Heater Sense Circuit Range/Performance Bank 2 Moderate
- P2506 Engine Control Module Power Input Signal Range/Performance High
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
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