P3478 — Cylinder 10 Exhaust Valve Control Circuit Performance

What Does P3478 Mean?

P3478 is a diagnostic trouble code indicating: Cylinder 10 Exhaust Valve Control Circuit Performance. This code relates to the powertrain system. The vehicle's computer detected a condition outside normal operating parameters and stored this code.

Symptoms of P3478

⚠️ Check Engine Light (MIL) illuminated
⚠️ Cylinder 10 Exhaust Valve not meeting expected output
⚠️ Degraded performance of related system
⚠️ Reduced engine performance

Common Causes

🔍 Cylinder 10 Exhaust Valve degraded from age or contamination
🔍 Mechanical wear in Cylinder 10 Exhaust Valve or related parts
🔍 Restriction or blockage affecting Cylinder 10 Exhaust Valve
🔍 Calibration drift in Cylinder 10 Exhaust Valve

Frequently Asked Questions

What does P3478 mean?

P3478 indicates: Cylinder 10 Exhaust Valve Control Circuit Performance. The vehicle's computer has detected that the Cylinder 10 Exhaust Valve is not operating within its expected parameters and stored this diagnostic trouble code.

Can I drive with code P3478?

You can drive short distances for essential trips, but schedule a diagnosis soon. Driving with P3478 for extended periods may cause additional problems.

How much does it cost to fix P3478?

Repair costs for P3478 typically range from $50 to $400, depending on the root cause. Simple wiring or connector repairs are on the lower end, while component replacement costs more. A proper diagnosis ($80–$150 at most shops) will identify the exact cause before committing to expensive parts.

What To Do Next

Possible Fixes

🔧 Inspect Cylinder 10 Exhaust Valve for contamination or wear
🔧 Replace Cylinder 10 Exhaust Valve
🔧 Address any related mechanical faults

1
Find your vehicle above
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2
Check for recalls
Go to nhtsa.gov/recalls and enter your VIN. Free repairs if covered.
3
Get a professional diagnosis
A code alone doesn't identify the exact failed part. A diagnostic ($50–$150) pinpoints the root cause.

P3478: Cylinder 10 Exhaust Valve Control Circuit Performance