Applicable Systems
EMCP 4.2
Symptoms
Coolant temperature gauge reading erratic or showing maximum; engine may derate due to false high temp reading.
Possible Causes
- Coolant temp sensor signal wire short to +5V or ground
- Sensor internal failure
- Sensor connector corrosion
Troubleshooting Steps
- Step 1: Check coolant temp sensor resistance at operating temp
Resistance matches temp-resistance chart - Step 2: Inspect sensor connector for corrosion/moisture
Connector clean and dry - Step 3: Check signal wire for short to +5V or ground
No shorts found - Step 4: Replace coolant temp sensor if resistance out of spec
New sensor resistance matches chart - Step 5: Clear code and verify temperature reading
Temperature reads normal 85-95C
How to Reset
Clear via Cat ET after sensor replacement.
Common Replacement Parts
- Coolant Temperature Sensor P/N: 213-9510
Frequently Asked Questions
- Q: What is normal engine coolant temperature?
Normal operating range is 85-95C. Above 105C triggers derate. Below 70C may indicate thermostat stuck open.
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Source: caterpillarfaultcodes.com CID list
Category: Heavy Equipment
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