Engine Coolant Temperature Sensor Signal Too Low
The KIOTI-P0117 (Daedong) diesel fault code means: Engine Coolant Temperature Sensor Signal Too Low. This is a moderate severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- moderate
- Estimated cost
- DIY sensor replacement $20-$60 for the sensor part. Professional diagnosis and repair $80-$250 depending on whether the fault is the sensor alone or a harness repair.
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Common Symptoms
- Cluster displays P0117 or a coolant temp warning at startup
- Coolant temperature gauge reads unusually low or pegs to the bottom of the scale even after warmup
- Engine may run rough or smoke more than usual because ECM is using a fallback fueling strategy
- DPF regeneration cycles may not trigger correctly because the ECM cannot confirm proper engine temperature
- Tractor may enter a reduced-power or derate condition to protect the engine
- Cold-start enrichment may stay active longer than normal, causing excessive black smoke at the exhaust
- Engine warning light illuminates on the instrument cluster and stays on
Probable Causes (Ranked by Likelihood)
- Coolant temperature sensor has failed internally, pulling the signal voltage abnormally low Very Likely
- Wiring harness between the sensor and ECM is shorted to ground, dragging signal below threshold Very Likely
- Corroded or loose connector at the coolant temperature sensor causing a low-resistance fault Likely
- Chafed or pinched wire in the engine harness contacting the block or frame Likely
- ECM connector pin pushed back or corroded at the ECM harness plug Possible
- Coolant sensor O-ring failed allowing coolant intrusion into the connector and shorting the circuit Possible
- ECM internal fault misreading a good sensor signal Less Likely
Step-by-Step Diagnostic Procedure
Step 1. Before you touch anything, let the engine cool completely so coolant pressure is zero. Locate the coolant temperature sensor. On most Daedong 3- and 4-cylinder engines it threads into the thermostat housing or the top of the block near the head. It has a 2-wire connector.
Step 2. Turn the key to RUN (do not start). Check the cluster coolant gauge. If it reads pegged at the bottom or ice-cold with no change, that confirms the ECM is seeing a voltage below roughly 0.2 V on the signal wire, which is what sets P0117.
Step 3. Unplug the coolant temperature sensor connector. Set your multimeter to DC volts, probe the signal wire in the harness-side connector (the wire going toward the ECM, not the sensor side) against a good chassis ground. You should see a reference voltage between 4.5 V and 5.0 V with the key ON. If you read 0 V or near 0 V, the harness signal wire is shorted to ground somewhere between the connector and the ECM. Trace the harness for chafing or pinch points.
Step 4. With the sensor still unplugged, switch your multimeter to resistance (ohms). Measure resistance across the two terminals of the sensor itself. A cold sensor (ambient temperature around 68 F / 20 C) should read roughly 2,000 to 3,000 ohms. A reading of 0 ohms or a few ohms means the sensor is internally shorted and needs replacement. A reading of OL (open) is a different fault and would set P0118 instead.
Step 5. Inspect the connector body and pins closely. Look for green corrosion, bent pins, or moisture inside the connector. If coolant is wet inside the connector housing, the O-ring on the sensor has likely failed. Clean the connector with electrical contact cleaner, dry it, and apply dielectric grease before reassembly.
Step 6. If the sensor resistance is in spec and the harness reference voltage is good with the sensor unplugged, plug the sensor back in and wiggle the harness while watching the cluster gauge. If the reading jumps or the code clears intermittently, you have a broken wire inside the insulation or a failing connector terminal. You will need to repair or replace that section of harness.
Step 7. If you replace the sensor and the code returns within a short drive, the problem is in the wiring or the ECM connector. At that point, pull the ECM harness plug and inspect the coolant temp signal pin for corrosion or a pushed-back terminal. This step requires care around the ECM and is best done by a Kioti dealer with a scan tool to confirm live sensor data before and after the repair.
Step 8. Clear the DTC using the instrument cluster code-clear procedure (hold the appropriate cluster button per your owner manual) or with a Kioti dealer scan tool over CAN. Run the engine to operating temperature and confirm the coolant gauge climbs normally and P0117 does not return.
Frequently Asked Questions
What does Kioti code P0117 mean?
It means the ECM is reading an abnormally low voltage on the coolant temperature sensor circuit. That usually points to a sensor that has shorted internally, a wire in the harness that is shorted to ground, or a corroded connector dragging the signal voltage down below the acceptable threshold.
Can I still operate my tractor with P0117 active?
You can run it for a short time to get the job done, but you should not ignore it. Without a valid coolant temperature signal, the ECM falls back to a fixed default value for fueling and DPF regen decisions. That means the engine may run richer than it should, DPF regen may not trigger on schedule, and you will not get a real overheat warning if the engine actually gets hot. Fix it soon.
How much does it cost to fix P0117?
If the sensor itself has failed, a replacement sensor costs roughly $20 to $60 and is a straightforward swap most owners can do in under 30 minutes with basic hand tools. If the problem is a shorted or chafed wire in the harness, a dealer repair could run $80 to $250 depending on how long the harness trace takes.
Will P0117 cause my tractor to overheat without warning?
Yes, that is a real risk. If the coolant temp sensor circuit is shorted, the cluster gauge may read cold or nothing even if the engine is actually running hot. Do not rely on the gauge to warn you of overheating while this code is active. Check the coolant level visually before each use and watch for steam or a rising temperature reading as a backup until the sensor is repaired.
P0117 on Other Platforms
The same code ID appears across other engines, vehicles, and equipment. Diagnostic flow varies by platform — see the matching breakdown: