P2681 on Lexus
Engine Coolant Bypass Valve Control Circuit/Open
P2681 on Lexus vehicles indicates engine coolant bypass valve control circuit/open. Au7o has documented this code across 1 Lexus model — most commonly on UX. 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.
Common Causes of P2681
- •Open/broken wiring in the bypass valve circuit
- •Faulty coolant bypass valve/actuator
- •Corroded or disconnected connector
- •Blown fuse
- •PCM driver fault
P2681 on Lexus by Model
Lexus UX(1 issue)
- Engine Coolant Flow Shut-Off (Bypass) Valve Leaks and Fails - 'Maintenance Required' Message, P268111/P2681152019-2021
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.
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View P2681 across all makes →Frequently Asked Questions
What does P2681 mean on Lexus?▼
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. On Lexus specifically, this code is documented across 1 model.
What causes P2681 on Lexus vehicles?▼
Common causes on Lexus: Open/broken wiring in the bypass valve circuit, Faulty coolant bypass valve/actuator, Corroded or disconnected connector, Blown fuse, PCM driver fault. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P2681 on a Lexus?▼
Repair costs vary widely depending on the root cause and specific Lexus model.
Which Lexus models have P2681 documented?▼
Au7o has documented P2681 on 1 Lexus model: UX.