1837011PE | Genuine Paccar® Actuator Bypass Valve

• Kenworth T680
• Kenworth T880
• Kenworth W900
• Peterbilt 567
• Peterbilt 579
• Peterbilt 589
• Other Kenworth and Peterbilt heavy-duty trucks using the MX-13 engine.

Important: This part does not fit every T680, T880, W900, 567, or 579. Fitment depends on:

• Model year
• Engine serial number (ESN)
• Emissions version (EPA10, EPA13, EPA17, EPA21)

• Improve cold-start warm-up
  • The valve partially closes the exhaust path after a cold start.
  • This increases exhaust back pressure, helping the engine and aftertreatment system reach operating temperature more quickly.
• Support emissions control
  • Higher exhaust temperatures help the diesel oxidation catalyst (DOC) and diesel particulate filter (DPF) operate efficiently.
  • The valve also helps maintain conditions needed for DPF regeneration.
• Provide exhaust braking
  • During deceleration, the valve can restrict exhaust flow to create back pressure.
  • This increases engine braking, reducing wear on the service brakes, especially when driving downhill.
• Optimize engine operation
  • The engine control module (ECM) continuously adjusts the valve position based on engine speed, load, temperature, and other sensor inputs.
  • This helps improve performance and overall efficiency under different operating conditions.

• Check Engine Light (CEL)
  • The engine control module (ECM) detects that the valve is stuck or not reaching the commanded position.
• Loss of engine power
  • If the valve is stuck partially closed, excessive exhaust back pressure can reduce engine performance.
• Poor fuel economy
  • Incorrect exhaust flow can make the engine run less efficiently.
• Reduced or no exhaust brake
  • On trucks equipped with an exhaust brake, braking performance may be weak or unavailable.
• Slow engine warm-up
  • If the valve stays open during cold starts, the engine may take longer to reach operating temperature.
• Frequent or failed DPF regenerations
  • Improper exhaust temperatures can prevent successful regeneration of the diesel particulate filter.
• High exhaust back pressure
  • A valve stuck closed can cause excessive back pressure, affecting turbocharger and engine performance.
• Rough idle or poor throttle response
  • The engine may feel sluggish or hesitate during acceleration.
• Unusual noises
  • Grinding, clicking, or buzzing from the actuator can indicate worn gears or a failing electric motor.
• Visible actuator problems
  • Damaged wiring, loose connectors, corrosion, or carbon buildup around the valve.