What it means
The 5 V supply rail D is below the expected level. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
How it works
Sensor Power Supply D is one of the module's regulated reference-voltage rails that feeds a group of sensors. This code sets when rail D falls below its expected level, often because the supply wire or a connected sensor is pulling it down, which can make several sensor readings implausible.
Common causes
Most likely first.
- Reference wire shorted to ground
- Sensor on the rail shorted internally to ground
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine light may be on
- One or more sensor readings may be implausible
- Rough running or reduced power may occur
How to diagnose it
- Review freeze-frame data and live sensor readings to identify which sensors on rail D show implausible values while the supply is low.
- Use vehicle wiring information to identify rail D's sensors, then inspect their connectors and shared wiring for chafing, moisture, corrosion, or loose pins.
- Measure rail D at an accessible sensor connector and observe whether the low reading changes while gently moving the harness.
- Following the manufacturer's isolation procedure, disconnect rail D sensors one at a time to check whether one internally shorted sensor is pulling down the shared supply.
- If the rail remains low with the sensors isolated, test the wiring for a short to ground and check the module regulator output against the manufacturer's specification.
Common fixes
- Clean and secure corroded or loose connectors on the rail D circuit.
- Repair a reference wire shorted to ground or damaged by chafing.
- Replace the sensor confirmed to be shorting the shared rail to ground.
- Repair the module only if its rail D output is confirmed below specification with wiring and sensors isolated.
Can I keep driving?
Avoid hard acceleration if the engine runs roughly or loses power, since a low shared reference can disrupt multiple sensor readings. Stop if operation becomes unsafe and arrange diagnosis 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.