P226C — Turbocharger/Supercharger Boost Control A Position Exceeded Learning Limit (6.7 Cummins (EGR + DPF, pre-SCR))

P226C on 6.7L Cummins 2007.5–2012 (EGR+DPF, pre-SCR) means the ECM has detected the VGT actuator’s learned travel is outside the allowable range. The platform…

Updated September 2, 2026

What it means

The ECM monitors the VGT actuator position feedback and the learned min/max travel. When the actual position deviates beyond the learned limits, P226C sets. On this platform the VGT is HE351VE with an electric actuator/position sensor and no wastegate/vacuum/boost solenoid.¹²

Most likely causes

1. VGT electric actuator/position sensor fault or internal wear — Actuator motor, gears, or integrated position sensor drift/failure prevents the ECM from achieving expected vane position; the learned travel exceeds limits. This is the common failure mode for the HE351VE electric actuator on 2007.5–2012 6.7L Cummins.¹²
2. VGT vane mechanism sticking / carbon buildup in unison ring and vanes — Soot/carbon in the turbo causes mechanical binding of the VGT vanes, so the actuator cannot reach commanded positions within the learned window, triggering the exceeded-learning-limit condition. Typical with HE351VE VGT on EGR+DPF trucks.¹²³
3. Actuator linkage or internal turbo mechanical binding — Broken or seized actuator linkage, damaged unison ring, or bent actuator arm prevents full travel; ECM sees position error beyond learned limits.¹²
4. Wiring/connector/ground issue to the VGT actuator — Corrosion, chafing, or poor ground to the electric actuator/position sensor causes erratic feedback, leading the ECM to deem learned travel out of range. Codes P2262/P226C/P0045/P0234/P0299 cluster around VGT actuator electrical/mechanical faults.¹²⁴⁵³
5. ECM calibration/learned values corrupted after recent repair or battery disconnect — Loss of learned actuator endpoints can cause an immediate P226C until a proper VGT relearn/adaptation is completed.¹

How to diagnose

1. Verify freeze frame and confirm P226C is present with related VGT codes P2262/P0045/P0234/P0299.
2. Inspect VGT actuator electrical connector for corrosion, moisture, and terminal tension; check harness for chafing near turbo and valve cover.
3. Command VGT vane position with a scan tool and observe actual vs desired position and actuator duty/feedback; look for limited travel, slow response, or position error.
4. Check for intake/exhaust restrictions and excessive soot that can cause vane sticking; inspect EGR system and DPF backpressure as contributing factors on EGR+DPF pre-SCR trucks.
5. If actuator response is erratic or travel is limited, perform VGT actuator relearn/adaptation per Cummins procedure and re-evaluate learned min/max limits.
6. If relearn fails or position error persists, evaluate the electric actuator/position sensor and VGT mechanical condition; the actuator is the common failure on HE351VE.

Parts and tools you may need

• Scan tool with Cummins bidirectional control for VGT position command and actuator relearn
• Digital multimeter
• Terminal test light
• Inspection mirror and borescope for turbo vane inspection

Rough cost and difficulty

Parts and labor vary by region and shop; actuator replacement and turbo service can be costly. Diagnose before replacing components.

When to see a pro

If the VGT actuator requires removal or turbo disassembly, or if high-pressure fuel system work is suspected, have a qualified diesel technician perform the work. Do not attempt high-pressure fuel line service. If the vehicle experiences sudden power loss while driving, stop and seek immediate professional diagnosis.

Sources