Q: Check engine light P1121 code. Still get warm air. What's the est. to see if the valve needs replacing or if its a faulty wire?

asked by on October 06, 2017

The check engine light is on. Sometimes it comes and goes but its usually on. The code is P1121. I'm wondering if the coolant valve needs replacing or if a faulty wire is causing the check engine light. I can still get cold air and warm air (maybe not hot, but definitely warm). I'd like to request a coolant valve replacement but I am wondering what happens if the part turns out to be fine and its a faulty wire that needs fixing instead. Thanks for your help!

Hi Willow. Thanks for contacting us tonight. The second generation Prius, model years 2004-2009, uses a 3-way valve to control coolant flow between the engine, the hot coolant storage tank (thermos), and the heater core - which is what causes hot air to blow from a heater. If something goes wrong with this valve, the “check engine” light comes on. The valve is prone to sticking, and Toyota actually issued a service bulletin on the replacement of the coolant flow valve. I have forwarded your inquiry to our sales and service department so they can look up the right part that needs to be replaced and verify that one of our mobile mechanics in your area can complete this service for you. I would strongly recommend having the electrical harness replaced at the same time, as it’s common for the harness to fail overtime.

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