SureTrack Real Fix: Too Much Boost

Real Fixes from the SureTrack® expert information resource are documented issues from actual shop repair orders and community discussions. Read on to see how SureTrack can help you correct issues that are not easily diagnosed using OEM information alone. SureTrack is currently available free with the purchase of a current Snap-on® diagnostic software version.

Turbochargers are a key component on some small diesel engines to get the maximum amount of power. But too much boost pressure can cause serious issues with the engine. Follow this Real Fix to see how a 2016 Mercedes-Benz Citan with a code P226B for high turbocharger boost pressure was diagnosed and the component that caused the problem.

Vehicle
2016 Mercedes-Benz Citan 1.5 Diesel

Title
P226B, Replaced Turbocharger

Complaint
The customer states the check engine light is on.

Cause
Connected a scan tool and found code P226B – Turbocharger/Supercharger Boost Pressure Too High – Mechanical. Performed a road test while the scan tool was used to monitor the live data and observed the actual manifold pressure was above the desired manifold pressure. Key off, inspected the turbocharger air tubes for evidence of damage and found no obvious faults. Inspected the turbocharger and the turbocharger air tubes for signs of excessive soot and found the turbocharger and turbocharger air tubes were clean. Key off, disconnected the electronic turbocharger actuator harness connector and inspected the terminals, but found no obvious faults. Removed the electronic turbocharger actuator from the turbocharger and inspected the actuator drive gear for damage and found no faults. With the electronic turbocharger actuator removed from the turbocharger, inspected the turbocharger gear and found no evidence of any damage. With the electronic turbocharger actuator removed, moved the turbocharger gear lever up and down to each stop limit to inspect for smooth movement and found the gear lever did not actuate smoothly. The results of these tests verified the turbocharger was faulty.

Correction
Replaced the turbocharger, cleared codes, performed a road test and verified the vehicle operated properly. The check engine light did not illuminate and no fault codes returned.


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About the Author

Nick Taylor

Nick Taylor is the SureTrack Community Administrator and a Senior Applications Specialist at Mitchell 1 with over 25 years of experience with electronic repair data systems. Nick previously worked in the automotive dismantling and engine rebuilding industries.