OBD-II trouble code
P06A8: Sensor Reference Voltage "C" Circuit Range/Performance
Application matters: C identifies the reference-voltage circuit designated by the manufacturer. Determine its actual monitored output and connected devices from the exact wiring information; the letter does not establish a location, regulator count or number of sensors.
Reference C failed its range/performance check. That result does not prove voltage stayed within a normal window, that only drift is possible or that the controller needs replacement.
Quick facts
- System
- Powertrain
- Category
- PCM / Electronics
- Severity
- High severity
- Driving guidance
- Stop safely and arrange diagnosis
- Repair cost range
- Get a vehicle-specific estimate after diagnosis.
- DIY difficulty
- Shop recommended
A code alone cannot establish whether driving is safe. Stop safely for a red brake or oil-pressure warning, overheating, severe misfire, stalling, or impaired braking or steering, and follow the owner's manual. Restraints faults can reduce crash protection even when the vehicle runs normally.
Part of a family with 3 codes
P06A8 is one of 3 codes covering sensor reference voltage range and performance faults. The identifier must be matched to the exact vehicle. Related codes can share a diagnostic approach, but their circuit, failure condition, and required tests can differ.
Read the full guide for this family →Browse every code in P0600–P06DE, or start from the full code library.
What does P06A8 mean?
P06A8 reports a range/performance condition on the sensor-reference circuit designated C. Use the full DTC and exact controller information to identify the monitored circuit. The designation does not establish how many physical regulators or sensors the vehicle has, which devices share this reference or where they are located.
In the cited 2024–2025 Ford gasoline summary, the Bosch Tricore example maps P06A8 to P0697_1C. It detects reference voltage outside its specified window. Range/performance therefore cannot be used as proof that the reference remained present and electrically in range, or as a synonym for a drifting-only fault. The separate low/high and circuit/open labels do not establish mutually exclusive physical causes.
Preserve the complete scan report and compare companion codes with the actual wiring information. A grouping can guide the investigation, but codes on one or several references do not isolate or exclude a shared supply, connection, attached device or controller problem by themselves. Nor must all affected sensor readings change in one predictable way.
Have qualified personnel check the indicated reference, supporting supplies/returns and connected circuits using the protected procedure. A present measurement may reveal an out-of-range condition; a single normal measurement may not reproduce the recorded event. The procedure determines whether further capture or isolation is needed. Do not disconnect sensors at random, bridge a reference to another supply or choose a controller because several codes appeared together.
Possible causes
- A wiring, terminal or connection fault affecting the identified reference
- An attached device loading the reference, where confirmed by the schematic and tests
- A short or interaction with another circuit demonstrated by diagnosis
- A supporting supply/return or controller fault established by the prescribed checks
Symptoms
- Check-engine warning with P06A8 stored
- Sensor-data or circuit faults requiring comparison with the installed wiring
- Running or response problems whose effects depend on the actual affected system
- Few noticeable symptoms despite a recorded reference-voltage fault
Diagnostic steps
Save the full scan report, code status, and available freeze-frame data before clearing anything. Confirm the reporting module, any failure-type suffix, and the procedure for the exact vehicle. The steps below are an overview; use manufacturer specifications and safety procedures for testing.
- 1.Save all full DTCs, status and event data before clearing anything. Record warnings, symptoms and recent work without assigning a cause from timing alone.
- 2.Identify reference C, its monitored connections and the actual attached devices from engine/controller-specific information. Do not infer a minimum hardware count from the letter.
- 3.Use companion codes as evidence to evaluate, not a rule that faults spanning several references must have a different cause.
- 4.Limit owner inspection to safely visible damage with ignition off and the engine stopped. Leave terminal probing, connected capture and component isolation to qualified personnel.
- 5.Have the specified reference, supply, return and circuit tests performed with protected equipment and the required connection states. Do not add a generic load, jumper a supply or repeatedly unplug devices to hunt for a result.
- 6.Repair the demonstrated cause, verify the required reference behavior and assess remaining companion faults. Neither one normal voltage reading nor clearing codes completes every confirmation.
Repair cost
Get a vehicle-specific estimate after diagnosis.
A trouble code alone does not price the repair. Ask the shop to identify the confirmed fault and itemize diagnosis, parts, labor, programming or calibration, and taxes.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with check engine light diagnosis preselected. Adjust labor rate and vehicle category to fit your situation.
Related repairs
These links are planning examples; the code does not confirm that any listed part has failed.
DIY vs shop
A qualified shop is recommended because this can involve control module programming and configuration, which generally needs manufacturer software and a stable supply throughout. Ask the technician what testing confirmed the repair.