2020 Toyota RAV4 P0128 Diagnosis

This case study from Chris Daniel is on our AccuFix platform. Chris is one of our newest contributors on AccuFix and brings us great content on late model Toyotas! Thanks, Chris!

Symptoms: P0128:07 stored in ECM, Coolant thermostat (coolant temperature below thermostat regulating temperature) mechanical failure. Vehicle taking too long to warm up, poor heat from vents.

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Step 1. Performed health check: P0128:07, and P0128 stored.

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Step 2. I verified the temperature at the thermostat inlet matches the coolant temp data PID. This indicated that the thermostat was stuck open. Specifications on opening temperature are 176-183*F

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Correction

Parts: Engine Coolant Thermostat / Water Inlet Assembly (Quantity: 1)

Description

Replaced the thermostat; it was stuck open all the time, causing excessive warm-up time.

Daniel Diagnostics …:32 pm