Fuel and air

P2599 — Turbocharger Boost Control Position at Low Limit

Severity: medium Drive with care, to a shop

What P2599 means

The engine control unit compares the commanded position of the boost control mechanism (a wastegate actuator or variable geometry vanes) with the actual position reported by its sensor. P2599 sets when the mechanism stays at its low limit and does not reach the commanded position. The turbo then cannot build the requested boost and the engine loses power.

Symptoms

  • Sluggish acceleration
  • Check Engine light on
  • Reduced power or limp mode
  • Unusual whistling or noise from the turbo
  • P0299 (underboost) may also be stored

Possible causes

  1. Boost leak, such as a split or loose intercooler hose or a loose clamp
  2. Wastegate stuck open
  3. Sticking variable geometry mechanism from carbon buildup
  4. Faulty boost actuator (electric or vacuum) or position sensor
  5. Vacuum line leak or damage
  6. Wiring or connector fault at the actuator
  7. Worn or failed turbocharger
  8. Badly clogged air filter

How to diagnose

  1. Scan for all codes and freeze frame data, noting P0299 or other boost codes
  2. Inspect the air filter, intercooler hoses and clamps for cracks, oil and loose fittings
  3. Check vacuum lines, control solenoid and vacuum pump if the actuator is vacuum operated
  4. Inspect the actuator and sensor wiring and connectors for corrosion, breaks and chafing
  5. Compare commanded and actual boost and actuator position in live data
  6. Use a scan tool to command the actuator and confirm it moves smoothly through its full range
  7. Check the turbo shaft play, wheel condition and free movement of the wastegate or vanes
  8. Pressure test the intake tract for leaks

Common fixes

  • Replace damaged hoses and tighten clamps
  • Replace the air filter
  • Repair wiring and connectors, or replace the actuator and position sensor
  • Replace faulty vacuum lines, solenoid or pump
  • Clean or replace the turbo if the geometry is seized or it is worn

Questions and answers

What does P2599 mean?

The turbo boost control actuator is sitting at its low limit and not moving to the commanded position. As a result the turbo cannot produce the requested boost.

Can I drive with P2599?

Briefly and carefully, yes, but power will likely be limited. Get it diagnosed soon to avoid damaging the turbo.

Does P2599 always mean a bad turbo?

No. Boost leaks, vacuum lines, wiring or the actuator are more common causes. Replace the turbo only after ruling those out.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.