01 Essential Preparations for a Long Drive: A Comprehensive Gu… • 02 Silent But Deadly: The Secret Dangers of Worn Ball Joints • 03 How to Read & Understand Live Data Streams from Your Car’s … • 04 Troubleshooting a Hard Brake Pedal: Causes and Solutions • 05 Cleaning Your MAF Sensor Can Go Wrong This Is How to Do It … • 06 Engine Cranks, Has Spark But Won't Start: Diagnose the Prob… • 07 This Is Why Your Car’s Exhaust Smells Like Sulfur • 08 Gearing Up: Manual vs. Automatic Transmissions in Modern Ca… • 09 P0023 B camshaft position - actuator circuit (Bank 2) • 10 Is the Land Rover Defender 2022 Worth a Trial? •

DTC codes / P34xx · Auxiliary emission controls / P3437

P3437Cylinder 5 Exhaust Valve Control Circuit/Open

P3437 indicates that the powertrain control module (PCM) has detected an open circuit or excessive resistance in the electrical path controlling the exhaust valve for cylinder 5. This circuit typically operates a solenoid or actuator that varies exhaust valve timing or lift to improve efficiency and emissions, and the PCM sets the code when the commanded state does not match the feedback signal.

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

Symptoms you may notice

  • Illuminated check engine light, often with no other symptoms
  • Rough idle or misfire sensation, especially when the engine is cold
  • Reduced engine power or sluggish acceleration under load
  • Decreased fuel economy due to improper valve timing
  • Intermittent hesitation or stumble during light-throttle cruising
  • Failed emissions test due to increased exhaust emissions

Common causes, most likely first

  1. Open or damaged wiring in the exhaust valve control circuit, such as a broken wire or corroded connector
  2. Faulty exhaust valve control solenoid or actuator that has failed electrically
  3. Poor electrical connection at the solenoid or PCM, including loose pins or water intrusion
  4. Failed PCM driver for the exhaust valve control circuit, though this is less common
  5. Mechanical binding or sticking of the exhaust valve mechanism, causing the actuator to draw excessive current or report an open circuit
  6. Aftermarket or damaged components installed in the circuit that do not meet specifications

How to diagnose and fix it

  1. Use a scan tool to verify P3437 is active and check for related codes or freeze-frame data
  2. Inspect the wiring harness and connectors at the cylinder 5 exhaust valve solenoid for damage, corrosion, or looseness
  3. Measure resistance of the exhaust valve control solenoid and compare to the manufacturer's specification
  4. Check for voltage and ground signals at the solenoid connector while commanding the circuit on and off with the scan tool
  5. Perform a continuity and short-to-ground test on the control circuit between the PCM and solenoid
  6. If electrical tests pass, inspect the exhaust valve mechanism for binding or carbon buildup that could cause an open circuit under load
  7. Replace the faulty solenoid, repair wiring, or reprogram/replace the PCM as indicated by test results, then clear codes and verify repair

When the wiring tests good but the code returns

  • A common oversight is assuming the solenoid is defective when the real problem is a chafed wire inside the loom that only opens when the engine shifts under torque.
  • The code can be set by a mechanical fault in the exhaust valve train that causes the actuator to overheat and fail electrically, so always inspect the valve mechanism after replacing a solenoid.
  • Some vehicles use a shared power or ground circuit for multiple cylinder valve actuators, so a fault in one cylinder's wiring can affect others and set companion codes.
  • Intermittent open circuits often leave no freeze-frame data, so a wiggle test of the harness while monitoring live data is more reliable than a static resistance check.
  • Replacing the PCM without first verifying the control circuit can introduce new programming issues and is rarely the correct fix for this code.

Can I keep driving with P3437?

You can usually drive the vehicle short distances to a repair shop, but avoid heavy acceleration or towing because the disabled exhaust valve control can cause poor performance and increased emissions. If the engine runs roughly or misfires, limit driving to prevent damage to the catalytic converter.

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.

Running on fumes Free guides aren't free to make. Top up the tank. Any amount, one time. Fuel the Garage