How to Solve the P268100 Coolant Bypass Valve Start Open Circuit?
3 Answers
p268100 Coolant Bypass Valve Start Open Circuit Solution is as follows: 1. First, you can replace the water pump assembly. The water seal is prone to aging and water ingress, which can easily cause motor damage, leading to the bypass valve start open circuit. 2. If the valve body is not damaged, you can replace the small electric water pump connected to the cooling booster. Engine knocking usually occurs in three situations: 1. The car lacks power. 2. The car lacks power, and the engine noise is too loud. 3. There is an obvious knocking sound from the cylinder. 4. In the first situation, some engine warning lights may come on, while others may not. In the second and third situations, the engine warning light will definitely come on.
I have experience dealing with the cooling system trouble code P268100, which mainly involves three steps: First, check the 15A fuse in the fuse box that powers the bypass valve—replace it if it's blown. Then, peel back the engine wiring harness and focus on inspecting the wires near the bypass valve for any abrasions or oxidized/greenish connectors—high temperatures this season make these issues common. Next, use a multimeter to measure the valve's resistance; the normal range should be between 10-20 ohms—if it reads infinity, the valve is faulty. Finally, perform a power-on test to listen for the 'click' sound of the valve actuating. Last month, while helping a friend fix this issue, I found that mice had chewed through the wiring harness, and wrapping it with electrical tape solved the problem. Remember to disconnect the battery before working on it, or you risk frying the control module. Don’t ignore this fault—it can lead to slow engine warm-up and a spike in fuel consumption.
With over 20 years of auto repair experience, I've encountered dozens of P268100 bypass valve circuit faults. Ninety percent are caused by loose wiring connectors, especially in older vehicles where copper corrosion tends to accumulate at the plug. Here's a practical trick: When the ignition is on but engine not started, have someone repeatedly turn the key to the ON position while you listen closely to the valve for faint electrical sounds. Alternatively, check if the coolant temperature warning light flashes simultaneously on the dashboard. If there's absolutely no response, directly open the fuse box cover and inspect the F37-position fuse - that small fingernail-sized thin strip. If it's burnt black, just spend five bucks to replace it. A stuck valve is more troublesome, requiring removal of the coolant pipe section behind the intake manifold. I recommend cleaning engine compartment wiring every two years and applying anti-oxidant spray as preventive maintenance.
