Whenever conducting repairs on a vehicle or engine under warranty, the manufacturer's instructions regarding repair and claim procedure should always be followed. This turbocharger troubleshooting material should be treated as supplementary and advisory only.

Engine systems are becoming more complex to meet the demands of emissions legislation and improved performance. At the same time, diagnostic systems are being incorporated into engine control modules (ECM) to help you troubleshoot when things go wrong.

To identify a problem more quickly all fault diagnosis should commence with a review of available fault code signals. There are 4 general categories related to engine-turbocharger sensors and engine-turbocharger performance that affect turbocharger troubleshooting.

Holset troubleshooting charts can be used to complement electronic fault diagnostics where available but they are equally effective when used for stand alone troubleshooting.

Holset turbochargers are designed and manufactured to last the lifetime of the engine. With basic engine maintenance (i.e. regular oil and filter changes) the turbocharger should provide long trouble-free service.

If you suspect a problem with a Holset turbocharger, the charts will help you quickly identify the correct cause of the problem and guide you to the most economical repair.

Holset Service has developed these charts using feedback from operators and repairers, to identify service conditions where additional troubleshooting material can be of significant assistance.

What problems do the charts cover?
The charts will assist you to determine the cause of engine-turbocharger related problems and provide you with a logical flow to the recommended repair procedures:

FT1 Low Power
Suspect maintenance, installation, problem or engine system malfunction is causing low power, black smoke or low boost pressure.
FT2 Oil Leakage
Suspect internal/external leaks at turbocharger evidenced by visible leakage, high oil consumption or blue smoke.
FT3 Blow-by
Suspect excess turbocharger blow-by when operating with either open crankcase breather or closed crankcase ventilation (CCV) system.
FT4 Noise
Suspect abnormal turbocharger noise when operating at various engine speed/load conditions.
FT5 Wastegates
Suspect wastgate turbocharger is either over or under boosting across all or part of operating range.
FT6 Pneumatic VGT
Suspect pneumatic actuated variable geometry turbocharger is either over or under boosting across all or part of operating range.
FT7 Electrical VGT
Suspect electric actuated variable geometry turbocharger is either over or under boosting across all or part of operating range.
FT8 ECM Fault Codes
Guide to possible link between engine control module fault code signal and Holset Turbocharger Diagnostic Chart.

In addition a set of quick turbocharger "Health Checks" has been developed, which can help with fault diagnosis without the need for any turbocharger disassembly.

This material should be particularly useful for repairs during the warranty period. It helps to improve fault-coding and reduce the number of turbochargers returned, where no fault is found after full disassembly and analysis by our warranty review staff.

The material in the charts is based on the following assumptions:

1. The engine and turbocharger has been installed according to the manufacturer's specifications.
2. The easiest repairs are done first.
3. Information on engine, fuel system, intake and exhaust, and vehicle troubleshooting solutions are covered by other material from the engine and equipment manufacturers.

How are the charts used most effectively?
The troubleshooting trees should be used as follows:

Step 1: Select the trouble shooting chart that best fits the fault you are investigating.
Step 2: Work from left to right along the first row of symbols describing the main problem or its symptoms.
Step 3: When you find the one which best describes the problem you are working on, follow the directions working down the page through the intermediate rows which provide more details on fault location and engine system conditions.
Step 4: The last rows provide specific inspections to be performed and their corrective actions. These are listed from left to right, starting with the easiest/quickest to perform.