Faulty engine coolant temperature sensor (internal short to ground); Short to ground in the signal wire between the ECT sensor and ECM; Corroded, loose, or damaged ECT sensor connector or terminals; Failed thermostat stuck open (causing the sensor to read low, but the code sets when the sensor signal is out of range low, so a stuck-open thermostat is less likely to set this specific code); ECM internal fault (rare but possible); Aftermarket sensor with incorrect resistance curve; Wiring harness chafed against engine components, shorting the signal wire to ground

DTC codes / Chrysler codes / P1117

P1117 · ChryslerEngine Coolant Temp Signal Out-Of-Range Low

Q: What does code P1117 mean?

Engine Coolant Temp Signal Out-Of-Range Low. P1117 on Chrysler vehicles means the engine control module (ECM) has detected an out-of-range low signal from the engine coolant temperature (ECT) sensor circuit. The ECM expects a voltage between roughly 0.3 and 4.7 volts, and a sustained low voltage indicates the sensor is reporting an unrealistically high coolant temperature or the circuit is shorted to ground.

P1117 on Chrysler vehicles means the engine control module (ECM) has detected an out-of-range low signal from the engine coolant temperature (ECT) sensor circuit. The ECM expects a voltage between roughly 0.3 and 4.7 volts, and a sustained low voltage indicates the sensor is reporting an unrealistically high coolant temperature or the circuit is shorted to ground.

SystemPowertrain

Code typeChrysler specific

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering

Symptoms you may notice

Check engine light illuminated, often with no other noticeable symptoms
Temperature gauge reads higher than normal or pegged hot
Poor fuel economy or rich-running condition due to incorrect fueling
Hard starting or rough idle when the engine is cold
Cooling fan may run constantly or not at all
Possible overheating if the sensor falsely reports a cold engine and the fan never engages

Common causes, most likely first

Faulty engine coolant temperature sensor (internal short to ground)
Short to ground in the signal wire between the ECT sensor and ECM
Corroded, loose, or damaged ECT sensor connector or terminals
Failed thermostat stuck open (causing the sensor to read low, but the code sets when the sensor signal is out of range low, so a stuck-open thermostat is less likely to set this specific code)
ECM internal fault (rare but possible)
Aftermarket sensor with incorrect resistance curve
Wiring harness chafed against engine components, shorting the signal wire to ground

How to diagnose and fix it

Verify the code with a scan tool and check freeze-frame data for coolant temperature and voltage
Inspect the ECT sensor connector and wiring for corrosion, looseness, or chafing
Measure resistance across the ECT sensor terminals and compare to Chrysler specifications for the current temperature
Backprobe the signal wire at the ECM and check for a short to ground with the sensor disconnected
Replace the ECT sensor if resistance is out of specification or the signal wire tests good
Clear the code and perform a road test to confirm the repair
If the code persists, diagnose the ECM and its ground circuits

Don't overlook the thermostat or wiring

A stuck-open thermostat can cause the coolant temperature to stay low, but P1117 sets when the sensor signal voltage is out of range low, which usually means a short to ground rather than a genuinely cold engine.
The ECT sensor on many Chrysler engines shares a ground circuit with other sensors, so a bad ground can skew the reading and set this code without the sensor itself being faulty.
Aftermarket coolant temperature sensors often have a different resistance curve than the OEM part, leading to false low-signal codes even when the sensor is new.
A shorted signal wire can be intermittent, so wiggle-test the harness while watching live data to catch the fault before replacing parts.
The ECM may substitute a default coolant temperature value when the sensor signal is out of range, masking driveability symptoms and making the code the only clue.

Can I keep driving with P1117?

You can usually drive the vehicle short distances to a repair shop, but avoid heavy loads or long trips because the ECM may be using a default coolant temperature and cooling fan operation could be compromised. If the temperature gauge shows overheating, stop and address the fault immediately.

Tools that help

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Guidance is general and written for Chrysler vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.