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DTC codes / P34xx · Auxiliary emission controls / P3488

P3488Cylinder 11 Exhaust Valve Control Circuit High

P3488 indicates that the powertrain control module (PCM) has detected an abnormally high voltage on the electrical circuit that controls the exhaust valve for cylinder 11, which is part of a variable valve timing or cylinder deactivation system. The PCM expects the circuit to draw current and pull the voltage low when the valve is commanded, but instead it sees voltage near battery positive, indicating an open circuit, a short to power, or a failed actuator.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaAuxiliary emission controls

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms
  • Rough idle or misfire that may be intermittent and worse when the engine is cold
  • Reduced engine power or a limp-home mode if the fault triggers protective strategies
  • Audible ticking or tapping from the valve cover area if the exhaust valve solenoid is stuck
  • Poor fuel economy or increased emissions due to improper valve timing
  • Hesitation or stumble during acceleration when the affected cylinder is commanded

Common causes, most likely first

  1. Open circuit in the exhaust valve control wire between the PCM and the solenoid, such as a broken wire or corroded connector
  2. Short to voltage on the control circuit, often from chafed wiring rubbing against a metal bracket
  3. Failed exhaust valve solenoid or actuator that has an open internal coil
  4. Poor electrical connection at the solenoid or PCM connector, including loose pins or water intrusion
  5. Faulty PCM driver for that specific cylinder circuit, though this is less common
  6. Aftermarket electrical accessories improperly tapped into the circuit causing voltage interference

How to diagnose and fix it

  1. Connect a scan tool and verify P3488 is current or pending, then check for any related codes that might indicate a different root cause
  2. Inspect the exhaust valve solenoid connector and the PCM connector for corrosion, loose pins, or pushed-out terminals
  3. Disconnect the solenoid and measure resistance across its terminals; compare to the manufacturer's specification to rule out an open coil
  4. With the solenoid disconnected and the key on, measure voltage on the control wire from the PCM to ground; it should be near zero with the circuit commanded off, and near battery voltage only when commanded on
  5. Perform a wiggle test on the harness while monitoring voltage or resistance to expose intermittent opens or shorts
  6. If the circuit tests good, command the exhaust valve solenoid on and off with the scan tool to confirm the PCM driver is functioning and the solenoid clicks
  7. Repair or replace the faulty wire, connector, or solenoid as needed, then clear the code and verify the repair with a test drive

Why cylinder 11 exhaust valve codes mislead

  • A high voltage code on an exhaust valve control circuit often results from a simple unplugged connector or a broken wire, not a failed solenoid, so always inspect the harness before condemning parts.
  • Cylinder 11 is typically part of a cylinder deactivation system on V8 or V12 engines, and a fault here may cause the PCM to disable the entire deactivation feature, leading to a noticeable drop in fuel economy without a misfire.
  • The PCM may set P3488 intermittently if the circuit is only open when the engine is cold or vibrating, so a wiggle test and freeze-frame data review are more reliable than a static resistance check.
  • Aftermarket remote starters or alarm systems tapped into the valve control wiring can introduce voltage spikes that mimic a short to power, so check for non-factory wiring before replacing the PCM.
  • Do not confuse this code with a mechanical valve problem; P3488 is strictly an electrical circuit fault, and replacing the solenoid without testing the circuit often leads to a repeat repair.

Can I keep driving with P3488?

You can usually drive the vehicle with P3488 set, but avoid heavy acceleration or towing because the affected cylinder may not be breathing correctly, which can lead to misfires and increased exhaust temperatures. If the check engine light starts flashing or you feel a strong misfire, stop driving and have the vehicle towed to prevent catalytic converter damage.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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