110 — Engine Coolant Temperature
J1939 diagnostic trouble code reference.
SPN 110 is a J1939 diagnostic code defined under the SAE J1939 standard used by heavy-duty Class 7 and 8 commercial vehicles for on-board diagnostics over the CAN bus. Temperature of the engine coolant The fault sits in the engine system, so the typical service path is targeted inspection of that subsystem before broader troubleshooting. This page summarizes what SPN 110 means in plain English, common causes when documented, the standard 5-step diagnostic flow, and any FMCSA roadside-inspection violations that cite this code.
- Code:
- 110
- System:
- J1939
- Category:
- engine
- Severity:
- High severity
Severity classification
110 is classified as High severity (critical).
Meaning
What this fault code indicates.
Typical Symptoms
Driver-observable indications commonly associated with this code.
- overheating
- engine shutdown
- derate
- coolant warning light
Cross-reference
The same physical condition is reported by these paired codes in the other diagnostic standard.
| System | Code | Title |
|---|---|---|
| OBD-II | P0118 | ECT Sensor Circuit High Input |
Related Codes
Codes commonly diagnosed alongside this one or sharing the same code family.
How to diagnose 110
- Confirm the code is current, not historical. Use a scan tool to read both Active and Historical (or Inactive / Logged) codes. SPN 110 matters most when it appears in the Active list. Historical-only codes can reflect a one-off event that has already cleared.
- Note any other codes set at the same time. Pull the full list of codes the ECM is reporting and write down which ones share a Freeze Frame timestamp with SPN 110. A simultaneous failure pattern often points to the root cause faster than any single code in isolation.
- Check the most-common cause for this code. Before replacing parts, check the most-common cause for this code (start with the simplest root causes — wiring, connector corrosion, sensor failure — before replacing larger components). The "Common causes" panel on this page lists the established root causes when we have published data — when it is empty, fall back to the OEM service manual or a licensed diagnostic database.
- Inspect the relevant component. Physically inspect the engine subsystem: connector pins, wiring harness, ground straps, and sensor body for damage, corrosion, or contamination. Many DTCs are wiring or connector faults rather than failed components.
- If unsure, take to a qualified diagnostic technician. If the code returns after repair, or if the actual fault is not obvious from the inspection, escalate to a shop with the proper licensed scan tool for the vehicle (heavy-duty trucks need a J1939-aware tool, not a generic OBD-II reader). Replacing parts based on the code alone is the most common cause of repeat repair costs.
Frequently asked questions about 110
What does SPN 110 mean? ▾
Is SPN 110 a serious problem? ▾
Can I drive with SPN 110 active? ▾
What's the typical cost to fix SPN 110? ▾
Will SPN 110 cause an emissions failure? ▾
How is SPN 110 different from related codes? ▾
Where can I find the official spec for SPN 110? ▾
What inspection violations might cite SPN 110? ▾
Related pages
Related
Data sources & freshness
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Census, SAFER, SMS, Licensing & Insurance (L&I), roadside inspections, crashes, and authority history.
Vehicle recall campaigns, defect investigations, and consumer safety complaints (SCRS).
Cross-border carrier registry and Canadian recall campaigns where applicable.
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