P0049 – Turbo/super charger turbine -over -speed

Patrick

By Patrick (Contact Me)
Last Updated 2016-03-23
Red Seal Certified Mechanic

Trouble CodeFault LocationProbable Cause
P0049 Turbo/super charger turbine -over -speed Mechanical fault

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What Does Code P0049 Mean?

The turbocharger is essentially an exhaust-driven air pump. It uses turbine and compressor wheels to use exhaust pulses from the engine to propel the turbine wheel which is paired with the compressor wheel. Which in turn creates pressure within the intake system (AKA Boost). Creating boost increases volumetric efficiency. In other words, increasing the amount of air that enters the combustion chamber. The ECU will activate this code the moment it detects the turbine shaft speed going faster then desired. It does this by monitoring the turbocharger speed sensor. Often times, the turbocharger speed sensor is a variable reluctant speed sensor. The ECM interprets the sensor reading , if speed is higher than limit it activates this code.

What are the common causes of code P0049 ?

  • Turbo speed sensor
  • Turbo speed sensor wires chafed/damaged
  • Wiring harness damage
  • Corroded or loose connections
  • Bad ground(s)
  • Aftermarket installed accessories
  • Low system voltage
  • Defective PCM

What are the symptoms of code P0049 ?

When this particular code is active you may or may not experience some of the following symptoms:

  • Lack of engine power
  • Engine de-rates (“limp mode”)
  • Reduced fuel mileage

How do you troubleshoot code P0049 ?

TOOLS:

Whenever you are working with cooling system electrical components and systems, some of the basic tools you will need are:

  • OBD code reader
  • Multifunction Multimeter
  • Basic socket set
  • Basic ratchet and wrench sets
  • Basic screwdriver set
  • Rag/shop towels
  • Battery terminal cleaner
  • Wheel chalks
  • Flashlight

SAFETY STEPS:

Whenever performing repairs of any kind on your vehicle, you must follow certain steps to keep you safe:

  • Wear PPE (Personal protective equipment)
  • Chalk wheels to prevent rollaway.
  • Park vehicle on flat and level surface

 

NOTE: Given the location of turbocharger and sensor, make sure to let engine cool down for 10-15 minutes to let exhaust cool down. The exhaust will be extremely hot!
hot-exhaust

BASIC STEP #1:

If there are other codes present for boost pressure, it would be a good idea to diagnose those first.

BASIC STEP #2:

Go ahead and pop the hood and first locate the turbocharger. It will be paired with the exhaust manifold. You may have to search around with a flashlight in order to identify. After doing a general visual inspection, look for the turbo speed sensor typically mounted directly on the turbocharger housing. Refer to service manual for specific sensor tests and values. Often times, you will need to measure the resistance between the pins of the sensor to make sure they are within desired limits. Its a quick way to rule out the sensor. If values aren’t within desired limits, throw it out and replace it with a new one (preferably OEM part.). Clear codes and test drive. No good? Continue to next step 

turbo-sensor

NOTE: Always disconnect battery before performing any electrical repairs.

BASIC STEP #3:

Visually inspect the turbo speed sensor harness. Often times, the harness will be routed on or near the exhaust manifold/downpipe. There is a lot of heat around this area when vehicle is being driven. Exhaust heat can cause a lot of damage to these harness’. If you find any damaged or exposed wire, repair and clear codes. Test drive.

BASIC STEP #4:

Using service manual, identify harness connectors involved with turbo speed sensor circuit. Unplug and test circuits using multimeter, checking for shorts to ground or power, or opens. If anything is not within desired limits, follow specific wire(s) along the harness and repair as necessary. Clear codes and test drive. If everything is good, reconnect connectors.

melted-insulation

BASIC STEP #5:

There is a good chance at this point that the ECM is faulty. If you feel brave, there may be a procedure in the service manual to help pinpoint. But, before doing anything crazy, bring vehicle to repair facility to further diagnose the issue. You never know, you may of missed something simple.

Codes Related to P0049

  • P003A – Turbocharger boost control module position exceeded limit.
  • P0046 – Turbocharger control circuit performance.
  • P006E – Turbocharger boost control module supply voltage low
  • P006F – Turbocharger boost control supply voltage high.
  • P00AF – Turbocharger boost control module performance.

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