CAT Engine 27383 Fault Code: Turbocharger #1 Compressor Inlet Pressure Sensor : Voltage Above Normal
Also called Engine Turbocharger 1 Compressor Inlet Pressure : Voltage Above Normal, Turbocharger #1 Compressor Inlet Pressure Sensor - Voltage Above Normal, Turbocharger #1 Compressor Inlet Pressure Sensor:Voltage Above Normal
Turbocharger #1 Compressor Inlet Pressure Sensor : Voltage Above Normal · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
CAT fault code 27383 (SPN 2738 / FMI 3) means the ECM has detected a signal voltage from the Turbocharger #1 Compressor Inlet Pressure Sensor that is above the normal operating range. This is an open circuit type diagnostic, and the ECM sets a default value for the parameter while the code is active. It applies to C13, C15, C175, C18, C27, and C32 engines.
Medium severity. This code does not shut the engine down on its own, but the ECM substitutes a default pressure value while active, which can affect turbo boost related calculations and engine performance monitoring. Diagnose it within the shift rather than ignoring it long term.
What does CAT Engine error code 27383 mean?
CAT fault code 27383 points to the Turbocharger #1 Compressor Inlet Pressure Sensor circuit. This sensor tells the ECM the pressure of the air entering the turbocharger's compressor side, which helps the ECM manage boost, fueling, and emissions related calculations.
The ECM continuously sends a pull-up voltage on the sensor's signal wire so it can watch for opens or shorts. When the ECM sees voltage on the signal circuit that is higher than the sensor's normal range, it logs this as an open circuit condition, which is the '-3' or 'Voltage Above Normal' code. This is distinct from a short circuit code, which would instead show an absence of pull-up voltage.
When this code is active, the ECM logs the fault and substitutes a default value for the pressure reading instead of using the sensor's actual signal. This keeps the engine running but means the ECM is no longer getting a real reading from that sensor location.
Common causes of 27383
- Intermittent electrical problem in the sensor circuit
- Damaged connectors or wiring between the sensor and the ECM
- A problem within the wiring harness itself
- A faulty Turbocharger #1 Compressor Inlet Pressure Sensor
- A faulty ECM (less common, checked only after wiring and sensor are ruled out)
How to troubleshoot CAT Engine 27383: first checks
- Inspect the sensor connector and related wiring for physical damage, corrosion, or loose pins. The supply voltage runs to terminal 1, sensor return to terminal 2, and signal to terminal 3 of the sensor connector, so check continuity and condition at each of these points.
- Wiggle test the harness and connector while watching for the code to change state, since an intermittent connection is a listed cause.
- Check the wiring harness between the sensor and the ECM for chafing, pinches, or corrosion, especially at any point where it may rub against engine components.
- If wiring and connectors check out, test or swap the sensor itself, since a faulty sensor is a listed cause.
- If the sensor and harness both check out good, suspect the ECM, but only after wiring and sensor have been ruled out.
How the code clears
No separate clearing step is listed. The code is logged and the ECM sets a default value for the parameter while active. Once the underlying wiring, connector, or sensor issue is repaired and the signal returns to a normal voltage range, the code should stop being active. Confirm the repair by cycling the key and checking that the fault does not return.
Affected models and serial ranges
27383 appears in our records across 6 CAT Engine models. Match your machine by model and serial number.
| Model | Serial ranges |
|---|---|
| C13 | Serial range not listed in source records |
| C15 | 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 27383 mean?
It means the ECM detected a voltage on the Turbocharger #1 Compressor Inlet Pressure Sensor's signal circuit that is above the sensor's normal range. This is treated as an open circuit condition on that signal wire.
Is SPN 2738 FMI 3 the same as CAT code 27383?
Yes. CAT fault code 27383 corresponds to SPN 2738 with FMI 3, which is the standard J1939 code for this sensor's voltage above normal condition.
Can I keep running the engine with this code active?
The engine will typically keep running because the ECM substitutes a default value for the affected parameter. However, because the ECM is no longer using the actual sensor reading, it's best to diagnose the issue as soon as practical rather than run indefinitely on a default value.
What usually causes this code?
The most commonly listed causes are damaged connectors or wiring, a problem within the harness, an intermittent electrical connection, or a faulty sensor. A faulty ECM is possible but should be considered last.
Which engines can set this code?
This code applies to C13, C15, C175, C18, C27, and C32 CAT engines.
Do I need to reset anything after fixing the wiring or sensor?
No separate reset procedure is listed. Repair the wiring, connector, or sensor issue, then verify the fault does not reappear after a key cycle or engine restart.