Cause
Corroded earth connection
An earth stud or strap that has corroded or loosened. Every voltage a module measures is referenced to its earth, so a poor one does not stop things working — it makes them report plausible, consistent and wrong readings across everything on that ground.
Earth points live where water collects: inner wings, chassis rails, the back of the engine. A spread of unrelated faults sharing nothing but a ground point is the signature.
Typically a moderate job.
Some of these codes mean you should stop driving
6 of the 98 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 (98)
Codes where this is a likely explanation first, rather than merely a possible one.
- P0371 Timing Reference High Resolution Signal A Too Many Pulses Likely for this code Stop driving High
- P0376 Timing Reference High Resolution Signal B Too Many Pulses Likely for this code Stop driving High
- P0485 Cooling Fan Power/Ground Circuit Likely for this code High
- P0494 Fan 1 Underspeed Likely for this code High
- 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
- P0604 Internal Control Module Random Access Memory (RAM) Error Likely for this code High
- P0606 Engine Control Module Processor Likely for this code High
- P0607 Control Module Performance Likely for this code High
- P0613 Transmission Control Module Processor Likely for this code High
- P0A8B 14 Volt Power Module System Voltage Likely for this code Moderate
- P0A8C 14 Volt Power Module System Voltage Unstable Likely for this code Moderate
- P2505 Engine Control Module Power Input Signal Likely for this code High
- P2506 Engine Control Module Power Input Signal Range/Performance Likely for this code High
- P2507 Engine Control Module Power Input Signal Low Likely for this code High
- P2509 Engine Control Module Power Input Signal Intermittent Likely for this code High
- P2604 Intake Air Heater A Circuit Range/Performance Likely for this code Moderate
- P2609 Intake Air Heater System Performance Likely for this code Moderate
- P2610 Engine Control Module Internal Engine Off Timer Performance Likely for this code Moderate
- P2A06 O2 Sensor Negative Voltage Bank 1 Sensor 1 Likely for this code Moderate
- P2A07 O2 Sensor Negative Voltage Bank 1 Sensor 2 Likely for this code Moderate
- P2A08 O2 Sensor Negative Voltage Bank 1 Sensor 3 Likely for this code Moderate
- P2A09 O2 Sensor Negative Voltage Bank 2 Sensor 1 Likely for this code Moderate
- P2A10 O2 Sensor Negative Voltage Bank 2 Sensor 2 Likely for this code Moderate
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.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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