Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Code 22, Coolant Temperature Sensor Circuit Open: Notes
OR SHORTED CIRCUIT
The Coolant Temperature Sensor (CTS) uses a thermistor to control signal voltage to the ECM. The ECM applies voltage on White wire to the sensor. When engine is cold, thermistor resistance is high, this means the ECM will see high signal voltage. As engine warms, thermistor resistance is less, this means the ECM will see low signal voltage. When engine reaches normal operating temperature, signal voltage will be approximately 1.5-2.0 volts at the ECM.
- This verifies that 4-5 volts is present at CTS connector.
- This checks ground side of CTS circuit.
- This determines if problem is caused by an open Brown wire or the ECM. Ensure ECM connectors properly fit.
- This determines if circuit or ECM is the problem. Ensure to check ECM connectors for proper fit.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.