Radiator Temperature Sensor Circuit Low (Chrysler)
What does P1199 mean?
The P1199 code means the vehicle's onboard diagnostic system has detected: Radiator Temperature Sensor Circuit Low (Chrysler). This is a moderate severity code.
Common Symptoms
- Check Engine Light on
- Temperature gauge reading abnormally high
- Cooling fans may not turn on when needed
- Possible engine overheating
- Erratic cooling fan behavior
Probable Causes (Ranked by Likelihood)
- Short to ground in radiator temperature sensor circuit Very High
- Internal short in radiator temperature sensor High
- Water intrusion in sensor connector Moderate
- Damaged wiring near the radiator Moderate
- PCM input circuit fault Low
Step-by-Step Diagnostic Procedure
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Read the radiator temperature sensor data on a scan tool
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Inspect the sensor connector for moisture or corrosion
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Measure sensor resistance and compare to specifications
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Check for short to ground in the sensor signal wire
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Replace the sensor if resistance is below specification
Frequently Asked Questions
Is P1199 dangerous?
P1199 can be dangerous because if the PCM thinks the radiator is very hot, it may not operate the cooling fans correctly. Monitor your actual engine temperature carefully and avoid driving if the engine is overheating.
Can water damage cause P1199?
Yes. The radiator temperature sensor sits in a location exposed to road spray, water, and debris. Water intrusion into the connector can cause corrosion and short circuits that trigger P1199.
Should I replace the sensor or the connector?
If the connector is corroded, replace both the sensor and the connector pigtail. A corroded connector will damage a new sensor. Apply dielectric grease to the new connector to prevent future corrosion.