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2017 IS 300 Coolant Leak - Suspect Water Pump, P0117 Code

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Mike T. · rep 0 · May 22, 4:46 AM · 1 replies · solved · Question

Vehicle: 2017 Lexus IS 300 AWD

Hey everyone,

I've got a 2017 Lexus IS 300 (AWD, 3.5L V6) with about 70,000 miles on it. Recently, I've noticed a sweet smell coming from the engine bay, and a small puddle of coolant under the front of the car after it's been parked for a while. The coolant reservoir level has also dropped significantly.

Yesterday, the check engine light came on, and when I scanned it, I got a P0117 code (Engine Coolant Temperature Sensor 1 Circuit Low). I'm thinking it might be a failing water pump, which I hear can be an issue on these models around this mileage. Has anyone else experienced this with their IS 300? What was your experience with getting it fixed?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 4:46 AM

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ClearTheCode admin answer:

It sounds like you've accurately diagnosed a common problem for the 2017 Lexus IS 300, especially with the P0117 code pointing to a cooling system issue. Here's what's likely happening and what to do:

  1. Understanding the P0117 Code:

    • P0117 - Engine Coolant Temperature Sensor 1 Circuit Low: This code indicates that the engine control module (ECM) is receiving a lower-than-expected voltage signal from the ECT sensor. While it directly points to the sensor or its circuit, a significant coolant leak can also indirectly affect the sensor's reading if it's no longer submerged in coolant or if the engine is overheating due to lack of coolant.

  2. Water Pump Failure:

    • Causes: The water pump on many Lexus V6 engines, including the 3.5L in your IS 300, is a known wear item. Over time, the internal bearings can fail, leading to leaks from the weep hole, or the gasket can degrade. The sweet smell and puddles are classic signs of a coolant leak, and the water pump is a very common culprit at 70,000 miles.
    • Symptoms: Besides visible leaks and smell, you might notice the engine running hotter than usual (though your P0117 might mask this), or a whining noise from the front of the engine.

  3. When to See a Shop:

    • Immediate Action: Do not delay taking your vehicle to a qualified mechanic or Lexus dealership. Driving with a significant coolant leak and a potential P0117 code can lead to severe engine overheating and catastrophic damage. Top off your coolant with the correct Lexus-approved fluid if you must drive it, but keep trips very short.
    • Diagnosis: The shop will perform a pressure test on the cooling system to pinpoint the exact source of the leak. They will also inspect the water pump, hoses, radiator, and thermostat housing. Given the mileage and symptoms, a water pump replacement is highly probable. They will also address the P0117 code, which might resolve itself once the cooling system integrity is restored and the sensor is properly immersed in coolant, or it might require a sensor replacement if it was damaged by overheating or lack of fluid.
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