Misdiagnosis of Returned Turbochargers

All turbochargers that are returned to the Warranty Parts Center (WPC) are inspected by GM Engineering for root cause failure. Many of the turbochargers from 2011-2016 Cruze, 2012-2018 Sonic, 2013-2018 Encore, and 2014-2018 Trax models equipped with the 1.4L turbocharged engine (RPO LUV, LUJ) being returned have no trouble found.

 

Prior to replacing a turbocharger, follow these inspections to help ensure a correct diagnosis.

 

DTC P0299

 

Do not replace the turbocharger if DTC P0299 (Engine Underboost) is set and one of the following is present:

  • Crack(s) at the wastegate port (this is normal) (Fig. 1)

 

Fig. 1

 

  • Broken wastegate solenoid valve port (replace solenoid valve)
  • Bent wastegate actuator port (replace actuator)
  • Missing wastegate actuator clip (replace clip)
  • Tamper paint have been removed, the seal broken, or the actuator has been adjusted
  • Broken bypass (recirculation) valve cover port or water/oil found inside the valve (clean the components) (Fig. 2)

 

Fig. 2

 

  • Restrictions in the induction system
  • Soft, twisted or collapsed air ducts
  • Restrictions to air flow to the turbocharger
  • Excessive exhaust system backpressure

 

Replace the turbocharger if DTC P0299 is set and one of the following is present:

  • Disconnected wastegate lever arm (crank) from the shaft (Fig. 3, #1. Wastegate lever arm pin; #2. Wastegate lever arm (crank); #3. Shaft)
  • Seized wastegate valve/linkage
  • Turbine wheel not rotating, broken turbine wheel shaft, or missing wheel nut

 

TIP: If DTC P0299 is set and no other issue has been found, always perform the Turbocharger Boost Control Test using GDS2 prior to replacing the turbocharger.

 

Fig. 3

 

Insufficient Watergate Preload

 

If the wastegate lever arm moves or wiggles with little effort while the actuator rod remains static, the preload is insufficient and the turbocharger must be replaced. (Fig. 4) This insufficient preload condition applies to 2011-2012 models with original equipment turbochargers. The wastegate actuator design was updated for the 2013 model year.

 

Fig. 4

 

Engine Oil Leaks

 

If there is a low engine oil level, excessive oil consumption, oil leaking into the induction or exhaust system, excessive oil in the PCV bypass hose, or excessive smoke or oil leaking at the tail pipe, verify the proper engine oil level and perform an inspection of the entire engine, checking for any aftermarket devices or custom modifications.

 

In addition, remove the turbocharger rubber outside air inlet duct — there will be normal oil staining in the turbocharger outside air inlet (Fig. 5) — and inspect the inlet tube for oil leaking into the opening of the turbocharger bore for the PCV bypass hose. Also check the turbocharger oil feed and return pipe for leaks, restrictions or damage.

 

Fig. 5

 

Inspect the exhaust system for the presence of oil as well. If oil is present, there may be a broken turbocharger turbine or compressor wheel. It is very unlikely that the turbocharger will leak oil internally if the turbine and compressor wheel shaft is not broken.

 

Cold Weather

 

DTC P0299 could set due to ice buildup in the induction system, Charge Air Cooler (CAC) and/or Boost Pressure sensor.

 

Engine Coolant Leaks

 

For coolant leaks at the turbocharger, check the coolant pipes and related connections. The turbocharger does not have any moving parts or seals for the engine coolant that would allow coolant to leak internally into the intake or exhaust system.

 

Turbocharger Replacement

 

If turbocharger assembly replacement is necessary, check the oil feed pipe and oil return pipe for any restrictions before reinstalling the turbocharger assembly. Replace the pipe if it’s restricted. Do not clean it. The oil return pipe may be damaged due to excessive heat if there is an inadequate oil supply to the turbo.

 

For 2011-2012 models, verify the Engine Control Module (ECM) has the latest calibration. The calibration enables the cooling fans to run after the vehicle has been turned off under certain conditions, allowing the turbocharger to cool in less time and reduce the likelihood of the oil coking in the oil feed pipe. Be sure to inform the customer that the fans may run after the engine is turned off.

 

Refer to #PIP5495 for additional diagnostic information and instructions on performing the Turbocharger Boost Control Test.

 

– Thanks to Raymond Haglund

 

 

Service Know-How
Diagnosing Communication U Codes before Replacing Parts

2 Comments

  1. Search for updated PIP5495B in the Service Information.

  2. Rick Tobias says:

    When trying to review PIP5495 this is the message I receive “The document is not available. It may have been removed from the system.” Is there another way to review that PI?