CAT Engine 1723 Fault Code: Intake Manifold Air Temp open/short to +batt
Also called CID 0172 FMI 03 Intake Manifold Air Temp open/short to +batt, Engine Intake Manifold #1 Temperature : Voltage Above Normal, Intake Manifold Air Temp Open/Short to +Batt, Intake Manifold Air Temp open/Short to +Batt, Intake Manifold Air Temperature Sensor : Voltage Above Normal, Intake Manifold Air Temperature Sensor Voltage Above Normal, Intake Manifold Air Temperature Sensor voltage above normal, Intake Manifold Air Temperature Sensor:Voltage Above Normal
Intake Manifold Air Temp open/short to +batt · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
CAT 1723 (SPN 105 / FMI 3) means the ECM sees intake manifold air temperature sensor signal voltage above 4.95 volts DC for more than 8 seconds (some versions use 4.8 volts for 1 second or 4.9 volts for 8 seconds), which the ECM reads as an open circuit or a short to a power source. The ECM substitutes a default intake manifold air temperature value and logs the code, and the warning light comes on if equipped.
Medium severity. This code does not shut the engine down, but it forces the ECM to use a fixed default intake manifold air temperature instead of the real reading. That can hurt cold starting, stability, and acceleration under load, so it should be diagnosed promptly rather than ignored.
What does CAT Engine error code 1723 mean?
CAT 1723 relates to the intake manifold air temperature sensor circuit on C10 through C32 series engines. This sensor tells the ECM how hot or cold the air entering the engine is, which the ECM uses to fine-tune fueling and timing for smoother starts and combustion.
When the ECM sees the sensor's signal voltage climb above roughly 4.95 volts DC for more than 8 seconds (some documentation uses 4.8 volts for 1 second, or 4.9 volts for 8 seconds), it decides the signal is invalid. Rather than guess, the ECM substitutes a default value, either 70 °C (158 °F) or 85 °C (185 °F) depending on the specific control software, and displays 'Voltage High' for Intake Manifold Air Temperature on the electronic service tool.
This is treated as an electrical fault, meaning the sensor itself is rarely the intended target of the ECM's diagnosis. The condition points at wiring, connectors, or a short to a power source somewhere in the sensor circuit.
What triggers a CAT Engine 1723 code?
The ECM sets this code when the intake manifold air temperature sensor signal voltage exceeds about 4.95 volts DC for more than 8 seconds (other listed versions cite 4.8 volts for 1 second, or 4.9 volts for 8 seconds). Some versions also require engine coolant temperature to be above -10 °C (15.0 °F), the ECM to have been powered for at least 2 seconds (or 3 seconds in another version), and diagnostic code 0168-01 to not be active.
Common causes of 1723
- Damaged, corroded, or loose connectors and wiring in the sensor circuit
- A short between the sensor signal wire and a power source (short to +battery)
- An open circuit in the sensor common or signal wire between the ECM and the sensor
- A faulty or failed intake manifold air temperature sensor
- A faulty harness or engine harness connector
- An intermittent wiring problem that only shows up under vibration or temperature change
- A faulty ECM (less common, but listed as a possible cause)
How to troubleshoot CAT Engine 1723: first checks
- Check the connector at the intake manifold air temperature sensor and at the ECM (P1/J1 or P2/J2 connector) for corrosion, bent pins, or partial insertion
- Inspect the wiring harness between the sensor and ECM for chafing, pinch points, or abrasion that could cause a short to a power source
- With the key off, disconnect the sensor and check for continuity and correct resistance across the sensor terminals to rule out a faulty sensor
- Check the sensor common line for an open circuit, since this line is shared between multiple temperature sensors
- Verify there is no active 0168-01 code, since that can affect whether 1723 is considered valid
- Confirm the ECM has been powered long enough (a couple of seconds) before assuming the code is a true fault versus a power-up transient
How the code clears
No separate clearing step is listed beyond fixing the wiring, connector, or sensor fault. Once the underlying open circuit or short to a power source is repaired and the signal voltage returns to a normal range, the ECM should stop logging the fault. Clearing the stored diagnostic code with a service tool after the repair is standard practice, though no specific reset procedure is described.
Affected models and serial ranges
1723 appears in our records across 10 CAT Engine models. Match your machine by model and serial number.
| Model | Serial ranges |
|---|---|
| C10 | Serial range not listed in source records |
| C11 | Serial range not listed in source records |
| C12 | Serial range not listed in source records |
| C13 | Serial range not listed in source records |
| C15 | Serial range not listed in source records |
| C16 | Serial range not listed in source records |
| C175 | Serial range not listed in source records |
| C18 | Serial range not listed in source records |
| C27 | Serial range not listed in source records |
| C32 | Serial range not listed in source records |
Frequently asked questions
What does CAT code 1723 mean?
It means the ECM detected the intake manifold air temperature sensor signal voltage running too high, above about 4.95 volts DC for more than 8 seconds in most versions, which it interprets as an open circuit or a short to a power source rather than a real high temperature reading.
Will CAT 1723 shut down my engine?
No shutdown is described for this code. The ECM logs the fault, turns on the warning light if equipped, and substitutes a default intake manifold air temperature value (70 °C / 158 °F or 85 °C / 185 °F depending on the software) so the engine keeps running, but tuning based on real intake air temperature is lost until it's fixed.
What symptoms will I notice with code 1723 active?
Documented symptoms include poor stability, poor cold running, poor acceleration under load, white smoke, and in some versions black smoke.
Is the sensor always the problem when I get code 1723?
Not necessarily. Damaged connectors, harness wiring shorted to a power source, open circuits in the signal or common wire, and even a faulty ECM are all listed as possible causes alongside a faulty sensor. Wiring and connector issues are the most commonly cited culprits.
Do I need special tools to diagnose 1723?
A digital multimeter to check sensor signal voltage and continuity, plus an electronic service tool to read the ECM's diagnostic status and confirm the 'Voltage High' flag, are the basic tools needed.
Can cold weather cause a false 1723 code?
Some versions of this diagnostic require engine coolant temperature to be above -10 °C (15.0 °F) before the code can become active, so very cold starts alone should not trigger it under those conditions.