P26A5: Engine Coolant Bypass Valve "B" Range/Performance
2 vehicles · 1 makes · $900-$2,200 repair
Most Reported On
P26A5 is an OBD-II diagnostic trouble code meaning “Engine Coolant Bypass Valve "B" Range/Performance.” This code means the computer determined that engine coolant bypass valve 'B' is operating outside its expected range or not responding as commanded. Coolant bypass valves regulate coolant flow through the engine to control warm-up speed and maintain a stable operating temperature. When valve 'B' underperforms, the engine may warm up slowly, run too hot or cold, or have weak cabin heat, so it should be diagnosed to protect the cooling system. This code is most commonly reported on 2020-2023 Subaru Outback, and 2021-2024 Subaru Legacy, with repair costs ranging from $900 to $2,200.
Common Causes
Typical Repair Cost
Based on 2 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
To diagnose P26A5, 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
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Vehicles Affected (2)
FAQ
What does P26A5 mean?
P26A5 stands for "Engine Coolant Bypass Valve "B" Range/Performance." This code means the computer determined that engine coolant bypass valve 'B' is operating outside its expected range or not responding as commanded. Coolant bypass valves regulate coolant flow through the engine to control warm-up speed and maintain a stable operating temperature. When valve 'B' underperforms, the engine may warm up slowly, run too hot or cold, or have weak cabin heat, so it should be diagnosed to protect the cooling system.
What are the most common causes of P26A5?
The most common causes of P26A5 are: Faulty or sticking coolant bypass valve 'B', Clogged or restricted coolant passages/lines, Damaged, corroded, or loose wiring and connectors, Low coolant or trapped air in the system, Faulty coolant temperature sensor input, PCM/ECM fault (rare). The specific cause varies by vehicle.
How much does it cost to fix P26A5?
Repair costs for P26A5 range from $900 to $2,200, depending on the vehicle and root cause.
Which vehicles are affected by P26A5?
Au7o has documented P26A5 across 2 vehicle models from 1 manufacturers: Subaru.
Sources (7)
- TSBSubaru Thermo Control Valve Warranty Extension / Service Information
- ForumSubaru Outback Forums: Thermo Control Valve (TCV) Class Action Lawsuit
- mediaTop Class Actions: Subaru class action alleges some vehicles have thermo control valve failure defect
- mediaTorque News: New Subaru Lawsuit Claims Vehicles Have Thermal Control Valve Failure Defect
- otherCarComplaints: Subaru Thermo Control Valve Recall Needed Alleges Lawsuit
- ForumSubaru XV Forum: TSB 09-80-21R Defective Thermo Control Valve - 2021 Model Year
- mediaClassAction.org: Lawsuit Says Subaru Thermo Control Valve Defect Can Cause Engine Overheating
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.