Code Definition

P1199 — Radiator Temperature Sensor input voltage too low

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: Chrysler

About P1199

P1199 is a manufacturer-specific powertrain diagnostic trouble code recorded for Chrysler vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1199 is stored, the module has detected a signal or supply voltage lower than the expected operating range; and a sensor-related fault — the reported value from the named sensor is out of spec.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

P1199 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

On Chrysler vehicles, P1199 sets when the PCM sees the radiator temperature sensor signal voltage fall below its calibrated minimum, which corresponds to an unrealistically hot reading and usually means a short to ground or a failed sensor. The radiator temperature sensor is a negative temperature coefficient thermistor whose resistance drops as it warms, so a signal wire shorted to ground or a sensor that has gone low resistance internally pulls the voltage down and mimics very high temperature. The PCM uses this input, often together with the engine coolant temperature sensor, to control the...

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