What it means
The DC/DC converter voltage sensor A circuit has an electrical fault, so its reading may be unavailable or unreliable.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The DC/DC converter changes high-voltage battery power into lower-voltage power for the vehicle's electrical system. The control module monitors voltage sensor A's circuit for a usable electrical signal and sets P0E31 when that circuit has a fault, making the reading unreliable or unavailable.
Common causes
Most likely first.
- Sensor failed
- Wiring or connector fault
Symptoms
- Hybrid/EV system warning light may turn on
- Reduced power or charging performance
How to diagnose it
- Record freeze-frame data and related converter codes, then compare sensor A's reported value with sensor B and other available voltage data.
- With the vehicle powered down as specified by the manufacturer, inspect sensor A's connector and harness for looseness, corrosion, pin damage, or chafing.
- Check the sensor A circuit's power, ground, and signal paths using the manufacturer's wiring diagram and specifications.
- If the wiring and connections are sound, test sensor A and its reference or ground circuit to distinguish a failed sensor from a circuit fault.
- After repair, clear the code and confirm sensor A reports plausibly during the manufacturer's prescribed converter checks.
Common fixes
- Reseat and secure the DC/DC converter voltage sensor A connector.
- Repair damaged wiring, terminals, or ground connections in sensor A's circuit.
- Replace voltage sensor A if testing confirms it has failed.
- Clear the code and verify sensor A's reading after the repair.
Can I keep driving?
The fault may reduce power or charging performance, so avoid long trips or situations where a loss of electrical support would be unsafe. If the vehicle shows a hybrid/EV warning or reduced power, stop in a safe place and arrange prompt diagnosis.
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.