What Does P3493 Mean?
The PCM detected an open circuit in cylinder 12's exhaust valve control circuit. This means electrical continuity is broken, preventing the system from activating or deactivating the exhaust valve mechanism.
Common Causes
40%
Open circuit in wiring harness to exhaust valve solenoid
30%
Failed exhaust valve control solenoid with internal open
20%
Disconnected or corroded electrical connector
8%
Broken wire at cylinder head entry point
2%
Failed PCM internal circuit
Diagnostic Steps
1
Step 1: Visually inspect connector at cylinder 12 exhaust valve solenoid for proper connection and terminal damage
2
Step 2: Measure resistance through exhaust valve control solenoid (typically 5-15 ohms); infinite resistance indicates open circuit
3
Step 3: Check continuity from PCM connector to solenoid connector in harness with solenoid disconnected
4
Step 4: Inspect wiring at cylinder head where harness may be damaged by heat or movement
5
Step 5: Test PCM output circuit by backprobing connector and checking for control signal
Estimated Repair Cost
$120 - $700
Parts + labor, varies by vehicle and location
The PCM detected an open circuit in cylinder 12's exhaust valve control circuit. This means electrical continuity is broken, preventing the system from activating or deactivating the exhaust valve mechanism.
The most common cause of P3493 (Cylinder 12 Exhaust Valve Control Circuit/Open) is: Open circuit in wiring harness to exhaust valve solenoid
Typical repair costs for P3493 range from $120 to $700, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive but fuel economy will suffer and engine may run rough at idle. Cylinder deactivation feature will be disabled.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P3493 to identify the root cause.
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Quick Info
Category
Powertrain
System
Variable Valve Timing/Cylinder Deactivation
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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