C0550: ECU Malfunction (Chassis)
4 vehicles · 2 makes · $250-$3,200 repair
Most Reported On
C0550 is an OBD-II diagnostic trouble code meaning “ECU Malfunction (Chassis).” This is a chassis code indicating an internal Electronic Control Unit (ECU) malfunction, typically within the ABS/electronic brake control module or a related chassis controller. It sets when the module runs its internal self-checks (memory, processor, or output circuits) and detects a fault it cannot recover from. Because the affected controller often manages braking and stability functions, ABS, traction control, and stability control may be disabled, with their warning lights on. Base hydraulic braking generally still works. This code is most commonly reported on 2005-2008 Chevrolet Uplander, 2015-2020 GMC Yukon XL, and 2000-2013 Chevrolet Silverado 1500, plus 1 other vehicle, with repair costs ranging from $250 to $3,200.
Common Causes
Typical Repair Cost
Based on 4 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
To diagnose C0550, you'll need an OBD-II scanner. Here are our recommendations at every price point.
ANCEL AD310 Classic OBD-II Scanner
by ANCEL
A simple, affordable code reader that reads and clears check engine codes. Great for quick diagnostics on any OBD-II vehicle (1996+).
- Read & clear engine codes
- View freeze frame data
- I/M readiness status
- No batteries or app needed
BlueDriver Pro Bluetooth Scanner
by BlueDriver
Bluetooth OBD-II scanner with a free companion app. Provides enhanced diagnostics, smog readiness, and repair reports sourced from a database of verified fixes.
- Enhanced diagnostics (ABS, SRS, transmission)
- Repair Reports with verified fixes
- Smog check readiness
- Free app (iOS & Android)
LAUNCH CRP123X OBD-II Scanner
by LAUNCH
A professional-grade handheld scanner that reads all four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
- Engine, transmission, ABS, SRS diagnostics
- Live data stream & graphing
- AutoVIN for vehicle identification
- Free lifetime updates via Wi-Fi
Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level diagnostic tablet with bi-directional control, active tests, and full system coverage. Ideal for serious DIYers and small shops.
- All-system diagnostics (25+ modules)
- Bi-directional control & active tests
- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
As an Amazon Associate, we earn from qualifying purchases. Prices are approximate and may vary.
Vehicles Affected (4)
Electric Power Steering Failure
Transfer Case Encoder Motor / Position Sensor Failure Causing Stuck 4WD or Service 4WD Message
Sudden Loss of Electric Power Steering (EPS) Assist
FAQ
What does C0550 mean?
C0550 stands for "ECU Malfunction (Chassis)." This is a chassis code indicating an internal Electronic Control Unit (ECU) malfunction, typically within the ABS/electronic brake control module or a related chassis controller. It sets when the module runs its internal self-checks (memory, processor, or output circuits) and detects a fault it cannot recover from. Because the affected controller often manages braking and stability functions, ABS, traction control, and stability control may be disabled, with their warning lights on. Base hydraulic braking generally still works.
What are the most common causes of C0550?
The most common causes of C0550 are: Internal failure of the ABS/EBCM control module, Low or unstable supply voltage / weak battery, Corroded or loose module power and ground connections, Software or memory corruption (may need reflash), Damaged module connector or harness, Electrical interference or recent jump-start/voltage spike. The specific cause varies by vehicle.
How much does it cost to fix C0550?
Repair costs for C0550 range from $250 to $3,200, depending on the vehicle and root cause.
Which vehicles are affected by C0550?
Au7o has documented C0550 across 4 vehicle models from 2 manufacturers: Chevrolet, GMC.
Sources (12)
- media2005 Chevrolet Uplander Steering Problems - CarComplaints
- media2007 Chevrolet Uplander Steering Problems - CarComplaints
- NHTSANHTSA vehicle page for 2015 GMC Yukon XL (complaints/recalls/investigations) — includes suspension-related owner complaints such as 'Service Suspension System' warnings
- NHTSANHTSA vehicle page for 2016 GMC Yukon XL (complaints/recalls/investigations) — searchable for Magnetic Ride Control/shock leak and suspension warning complaints
- NHTSANHTSA vehicle page for 2017 GMC Yukon XL (complaints/recalls/investigations) — includes owner complaints that may reference MRC damper failures and 'Service Suspension System' messages
- NHTSANHTSA vehicle page for 2018 GMC Yukon XL (complaints/recalls/investigations) — source for verifiable suspension/MRC-related complaints and warning messages
- RecallChevrolet HHR Recalls (EPS recall 14V153) - Cars.com
- article2006 Chevrolet HHR Steering: Electric Power Assist System Problems - CarComplaints
- article2009 Chevrolet HHR Steering: Electric Power Assist System Problems - CarComplaints
- ForumPower Steering failure - Chevy HHR Network
- RecallNHTSA Part 573 Safety Recall Report 14V-153 (GM EPS assist loss)
- TSBGM Special Coverage Adjustment #14119 - Electric Power Steering Assist (lifetime EPS motor, 2006-2009 HHR non-turbo)
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.