What it means
Input power line A voltage below expected range. A communication loss with this module breaks any function relying on its data — diagnostic tools may show 'no response' and dependent modules can fall into limp mode.
At a glance
- Usually lights the warning light of the system that lost communication
- The engine or gearbox may go into limp mode
How it works
Input Power A is a supply line monitored by a control module. This code sets when the voltage on that specific input is below the expected range, which can interrupt the module's operation or communication.
Common causes
Most likely first.
- Weak battery or high supply resistance
- Gateway module routing CAN messages incorrectly
- CAN terminating resistor (120 Ω) drifted out of spec
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
How to diagnose it
- Scan all modules and note whether multiple power-related codes appear, since low battery voltage can affect several systems.
- Check freeze-frame and live data for Input Power A and battery voltage at the time the fault occurred.
- Inspect the battery connections, Input Power A fuse, wiring, connectors, and grounds for looseness, corrosion, or damage.
- Measure voltage at the module's Input Power A connection during the fault and check voltage drop along the supply path against the manufacturer's specification.
- If the supply measures correctly, check gateway routing and CAN network termination for communication faults that may be recorded alongside the low-power code.
Common fixes
- Charge or replace a weak battery after confirming its condition.
- Clean and tighten battery, supply, or ground connections.
- Replace a failed fuse after checking for the cause of the low voltage.
- Repair high-resistance or damaged Input Power A wiring.
Can I keep driving?
Avoid driving if the vehicle stalls, has widespread electrical warnings, or enters limp mode; low module voltage can cause systems to shut down unpredictably. If it runs normally, limit use and address the low supply promptly.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.