P06D8

What it means

P06D8 means the engine control module has detected that the sensor reference voltage supplied on circuit F is higher than the expected range, which is normally around 5 volts. The module powers several sensors from this shared supply, so a high reading suggests a short to a higher voltage or a fault inside the module's supply. Which sensors share circuit F depends on the vehicle and engine, so check the wiring information for the specific model.

Symptoms

• Engine warning light on
• Reduced power or the engine running in limp mode
• Rough running or poor throttle response
• Hard starting or no start
• Other sensor fault codes stored at the same time
• Erratic or implausible readings on several sensors

Possible causes

• Wiring fault on the reference supply circuit, such as a short to battery voltage or to another higher-voltage wirelikely
• Damaged, corroded or loose connector terminals on one of the sensors sharing circuit Flikely
• Open circuit on a sensor ground return, causing the supply to read highpossible
• Faulty sensor with an internal fault affecting the shared supplypossible
• Faulty engine control module reference voltage regulatorrare
• Poor module power or ground connection, or incorrect or outdated module software where this is a known cause for the vehiclerare

How to diagnose

1. Read all stored codes and freeze frame data, noting any other sensor circuit codes that point to a shared supply
2. Look up the wiring diagram to identify which sensors are on reference circuit F for this model and engine
3. Visually inspect the wiring, connectors and terminals of those sensors for chafing, water ingress, corrosion or pushed-back pins
4. Check the battery voltage and the module power and earth connections for good condition
5. With the ignition on, measure the reference voltage at the sensor connectors and compare it with the specification
6. Check each sensor ground circuit for continuity and resistance back to the module
7. Unplug the sensors on the circuit one at a time and see if the voltage returns to normal, which identifies a faulty sensor or a shorted section of wiring
8. Check for any applicable software updates or technical bulletins for the vehicle before considering the module

How to fix

• Repair or replace any damaged, chafed or shorted wiring on the reference supply circuit
• Clean, repair or replace corroded or damaged connectors and terminals
• Repair open or high-resistance sensor ground connections
• Replace the sensor found to be causing the high reference voltage
• Replace or repair the engine control module only after the wiring and sensors are proven good
• Update the module software if a known fault with the existing calibration is confirmed for this vehicle

Can I keep driving?

Nearby codes

• P06D7GenericSensor Reference Voltage F Circuit Low
• P06D9GenericSensor Reference Voltage F Circuit Range/Performance