P2678 moderate

Actuator Supply Voltage 'C' Circuit High

The P2678 code means the vehicle's onboard diagnostic system has detected: Actuator Supply Voltage 'C' Circuit High. This is a moderate severity code.

My Garage →
Keep driving?
Short distances only
DIY difficulty
moderate
Estimated cost
$150 - $600 (parts and labor)
Recommended Tool
ANCEL AD310 OBD-II Scanner

Best-selling code reader on Amazon. Reads and clears check engine codes on any 1996+ vehicle. Under $30.

Check Price on Amazon

Affiliate link -- we earn a commission at no extra cost to you.

Every Tech Needs This
AstroAI Digital Multimeter

Essential for diagnosing sensor codes, checking voltage, and testing circuits. Under $15 and pays for itself on the first job.

Check Price on Amazon

Affiliate link -- we earn a commission at no extra cost to you.

Common Symptoms

  • Check Engine Light on
  • Incorrect actuator operation
  • Possible overcharging symptoms
  • Battery light may illuminate
  • Engine control system errors

Probable Causes (Ranked by Likelihood)

  • Alternator voltage regulator failure causing overcharge Very High
  • Short to power in circuit C wiring High
  • Damaged wiring insulation causing short Moderate
  • PCM internal fault Low

Step-by-Step Diagnostic Procedure

  1. Read freeze frame data and confirm P2678 is present

  2. Test alternator voltage regulation

  3. Measure circuit C voltage at multiple points

  4. Inspect wiring for damaged insulation or shorts

Frequently Asked Questions

What does P2678 mean?

P2678 indicates an issue with the actuator supply voltage 'c' circuit high. This voltage circuit powers various engine actuators and sensors critical for proper engine operation.

Can I drive with a P2678 code?

You can drive short distances, but multiple engine systems may be affected. Have the charging and wiring systems checked promptly.

How much does it cost to fix P2678?

Repairs typically cost $150 - $600. A blown fuse is a quick fix, while alternator or wiring repairs cost more.

Sources

This page is built from documented references. Verify against your own service info before repair work.

Explore More

Search codes Vehicle-specific fixes Guides By make

Was this helpful?

Share carcodefinder.com with a friend who needs to decode their check engine light.

Browse by symptom → Read repair guides → Fixes by vehicle →