P2681: How to Diagnose & Fix — Engine Coolant Bypass Valve Control Circuit/Open
2 vehicles · 2 makes
How to diagnose and fix P2681: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Toyota RAV4 · 2019–2021
Toyota Customer Support Program 24TE04 covers certain 2019-2021 RAV4 and RAV4 Hybrid vehicles and certain 2021 RAV4 Prime vehicles when a small engine-coolant leak from the flow shut-off valve is verified. Coolant may drip onto other components and can produce an Engine Maintenance Required message or abnormal air-conditioning operation. Toyota T-SB-0112-24 Rev1 separately applies when that message is accompanied by DTC P268111 and/or P268115. These sources do not support the old 2019-2023 scope, 2,000-report count, generic P0128/P2181 mapping, catastrophic-engine claim or fixed repair price.
Common Symptoms
- Engine Maintenance Required message
- DTC P268111 and/or P268115
- Small engine-coolant leak at the flow shut-off valve
- Abnormal air-conditioning operation associated with the documented condition
How to Fix
Check coolant level only when the engine is cool, record the exact message and diagnostic codes, and have an authorized Toyota dealer verify VIN eligibility and the CSP or bulletin condition. The CSP primary coverage ended November 30, 2025; secondary coverage is 10 years from first use or 100,000 miles, whichever occurs first. If eligible and verified, Toyota states the covered water valve or water-bypass hose assembly repair is performed at no charge. T-SB-0112-24 Rev1 identifies updated hose assemblies 16260-F0300 for gasoline RAV4 and 16260-F0310 for RAV4 Hybrid/Prime, plus Toyota Super Long Life Coolant, but parts should not be ordered until the exact diagnostic and VIN gates are met. Otherwise continue cooling-system diagnosis; an initial diagnostic fee may apply when the condition is not covered.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Toyota 16260-F0310 water-bypass hose assembly
out-of-coverage replacement for a verified hybrid/Prime flow-shutoff-valve hose-assembly condition Fitment/availability: T-SB-0112-24 updated branch for covered RAV4 Hybrid and 2021 RAV4 Prime A25A-FXS applications; verify VIN, P268111/P…
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Owner tips & cautions
- WarningDo not open the cooling system while hot. Record coolant level, the exact warning text and all diagnostic codes before topping off or clearing codes.
- TipAsk the dealer to document VIN eligibility, first-use date, mileage and whether the condition qualifies under CSP 24TE04 or T-SB-0112-24 Rev1.
Sources for this issue (2)
Lexus UX · 2019–2021
The M20A-FKS in the UX 200 uses an electrically actuated coolant flow shut-off valve (also called the coolant bypass or control valve) that blocks flow through the block during warm-up to speed the engine to operating temperature. On 2019-2021 UX 200 vehicles the valve develops a small external coolant seep and the internal actuator circuit fails, setting P268111 (bypass valve circuit short to ground) or P268115 (circuit short to battery or open) and posting an 'Engine Maintenance Required' message in the multi-information display. The leak is slow and often mistaken for a non-issue, but coolant dripping onto surrounding components has been documented to cause A/C system malfunction as well. Lexus issued TSB L-SB-0051-24 (Toyota's parallel bulletin is T-SB-0112-24) directing replacement with an updated valve, superseding part 16671-F2010 with 16671-F2030. This is a UX 200 issue tied to the Dynamic Force gasoline engine family - the UX 250h hybrid uses a different cooling architecture and is not listed in the bulletin's applicability.
Common Symptoms
- 'Engine Maintenance Required' message in the multi-information display
- Check engine light
- Small coolant seep/drip near the front of the engine
- Low coolant level over time
- Slow warm-up or erratic temperature gauge behavior
- Air conditioning performance loss from coolant contamination of adjacent components
How to Fix
Replace the coolant flow shut-off valve with the updated part (16671-F2030, superseding 16671-F2010) and refill/bleed the cooling system per TSB L-SB-0051-24. Critically, 2019-2020 UX 200 vehicles are covered by Lexus Customer Support Program 24LE02 (Toyota's version is 24TE04), which pays for the repair regardless of mileage - call any Lexus dealer with the VIN and ask them to check 24LE02 before paying out of pocket. Do not simply clear the code: the valve does not recover.
Sources for this issue (3)
Find P2681 by make
Browse every documented model and issue for your make.
P2681 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P2681 mean?
P2681 stands for "Engine Coolant Bypass Valve Control Circuit/Open." The engine coolant bypass valve routes coolant flow (e.g., to control warm-up or flow paths). The PCM commands it and detects an open in its control circuit, so the valve cannot be operated.
What are the most common causes of P2681?
The most common causes of P2681 are: Open/broken wiring in the bypass valve circuit, Faulty coolant bypass valve/actuator, Corroded or disconnected connector, Blown fuse, PCM driver fault. The specific cause varies by vehicle.
How much does it cost to fix P2681?
Repair costs vary widely depending on the root cause and vehicle.
Which vehicles are affected by P2681?
Au7o has documented P2681 across 2 vehicle models from 2 manufacturers: Lexus, Toyota.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.