CAT Engine 2733 Fault Code: Turbo Outlet Pressure open/short to +batt
Also called Turbo Out Press Open/Short to Batt+, Turbo Outlet Pressure Open/Short to +Batt, Turbo Outlet Pressure Open/Sort to Batt+, Turbo Outlservice tool Pressure open/short to +batt, Turbocharger Outlet Pressure Sensor : Voltage Above Normal, Turbocharger Outlet Pressure Sensor Voltage Above Normal, Turbocharger Outlet Pressure Sensor voltage above normal
Turbo Outlet Pressure open/short to +batt · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
CAT fault code 2733 (SPN 102 / FMI 3) means the ECM sees the turbocharger outlet (compressor outlet) pressure sensor signal reading above 4.8 volts DC (some versions cite 4.95 volts at zero rpm), which the ECM interprets as an open circuit or a short to battery voltage. The ECM flags turbo outlet pressure as invalid data and substitutes a default value, which can pull engine power. This affects C10, C12, C15, C16, and C27 engines.
Medium severity. The engine will keep running but power will be reduced because the ECM cannot trust boost pressure data for fuel ratio control. It is not an immediate stop-engine emergency, but it should be diagnosed before running the machine under load for extended periods.
What does CAT Engine error code 2733 mean?
The turbocharger outlet pressure sensor, also called the turbo compressor outlet pressure sensor, tells the ECM how much boost pressure the turbo is producing. The ECM uses this reading to figure out inlet manifold pressure, which it then uses to control the air/fuel ratio during acceleration through what CAT calls the fuel ratio control limit (FARC). This works similarly to the fuel ratio control found on engines with a mechanical governor.
Code 2733 sets when the ECM sees the sensor's signal voltage climb above 4.8 volts DC (one version specifies 4.95 volts DC at zero rpm) for a sustained period. This is either a genuine short to battery voltage on the signal wire, or an open circuit that the ECM reads the same way, since an open signal line tends to float high just like a short to +battery.
Once the code sets, the ECM can no longer trust the sensor's data. It flags turbo outlet pressure as invalid and substitutes a default value (0 kPa / 0 psi in most versions, or 100 kPa / 14.5 psi in the zero-rpm version). Because boost pressure feeds directly into fuel/air ratio limiting, the ECM responds with reduced power output until the fault clears.
What triggers a CAT Engine 2733 code?
The ECM reads turbo compressor outlet pressure signal voltage above 4.8 volts DC for at least 0.24 seconds (one version says 1 second) after the ECM has been powered for at least two seconds (another version says three seconds). A separate version states the fault sets when signal voltage exceeds 4.95 volts DC for at least two seconds with engine speed at zero rpm. On versions with cross-checks, the code will not set if diagnostic codes 262-03 (5 volt sensor supply short to +battery) or 262-04 (5 volt sensor supply short to ground) are already active.
Common causes of 2733
- Damaged, corroded, or loose connectors, pins, or sockets in the sensor wiring, including connectors not fully seated
- Open circuit or short circuit in the harness, including a signal wire shorted to +battery, a signal wire shorted to the sensor common wire, or an open in the 5-volt supply wire
- Corrosion, abrasion, or pinch points in the wiring harness
- A faulty or failed turbocharger outlet pressure sensor that needs replacement
- An incorrect sensor installed on the engine
- Seals out of place at the sensor mounting
- Leaks in the pressure sensing system, including vacuum leaks
- A defective ECM (less common, checked after wiring and sensor are ruled out)
- Low resistance between two or more wires in the harness
- An intermittent connection problem
How to troubleshoot CAT Engine 2733: first checks
- Turn the key off, then back on, and check for the code on the diagnostic lamp or scan tool before disturbing anything, since an intermittent wiring fault may clear on its own
- Inspect the sensor connector and ECM connector for corrosion, bent pins, or a connector that is not fully seated; reseat and clean as needed
- With the key on and engine off, check the sensor signal wire (ECM pin -9) and 5-volt supply wire (ECM pin -63) for a short to +battery voltage using a multimeter
- Check the sensor return/common wire (ECM pin -6) for continuity and confirm it is not open or shorted to the signal wire
- Inspect the wiring harness routing for chafing, pinch points, or abrasion damage between the sensor and the ECM
- Verify the correct sensor part is installed; an incorrect sensor can read outside the expected voltage range
- Check for 262-03 or 262-04 diagnostic codes active at the same time, since a 5-volt supply fault can cause this code to set as well
- Inspect the sensor mounting and seals for leaks in the pressure sensing path
- If wiring and sensor check out, test the sensor itself, and consider ECM as a last resort if all else is confirmed good
How the code clears
No separate clearing step is listed beyond repairing the root cause. Once the wiring, connector, or sensor issue is fixed and voltage returns to the normal operating range, the ECM should stop setting the active code. The ECM performs an automatic calibration of pressure sensors during the first five seconds the ECM is powered as long as the engine is not cranked during that window, so cycling the key without cranking may be part of confirming a repair. The code will remain logged in ECM memory as a historical fault until cleared with a diagnostic scan tool.
Affected models and serial ranges
2733 appears in our records across 5 CAT Engine models. Match your machine by model and serial number.
| Model | Serial ranges |
|---|---|
| C10 | Serial range not listed in source records |
| C12 | Serial range not listed in source records |
| C15 | Serial range not listed in source records |
| C16 | Serial range not listed in source records |
| C27 | Serial range not listed in source records |
Frequently asked questions
What does CAT code 2733 mean?
It means the ECM sees the turbocharger outlet pressure sensor signal voltage above 4.8 volts DC (or 4.95 volts DC at zero rpm), which it interprets as either an open circuit or a short to battery voltage on that sensor's wiring.
Will code 2733 cause a loss of engine power?
Yes. The ECM flags the turbo outlet pressure reading as invalid and substitutes a default value, which the systems response describes as causing low power since the ECM cannot properly manage the fuel/air ratio without a valid boost pressure signal.
Is it safe to keep operating with this code active?
The engine will typically keep running, but expect reduced power. It is best to diagnose the wiring and sensor as soon as practical rather than running the machine under heavy load indefinitely.
What is the most common cause of this fault?
Damaged, corroded, or loose connectors and wiring are listed first and most often, followed by an open or short circuit in the harness and a failed sensor. ECM failure is possible but should be the last thing checked.
What voltage should the turbo outlet pressure sensor read normally?
Normal sensor output is a variable DC voltage between 0.2 and 4.8 volts DC, corresponding to a pressure range of 33 to 326 kPa (4.8 to 47.3 psi). The sensor receives a regulated 5.0 volts DC (some versions say 5.0 ± 0.2 VDC) supply from the ECM.
Does this code affect other pressure sensors on the engine?
The troubleshooting approach is shared with other analog pressure sensors on the engine, including the engine oil pressure sensor, injection actuation pressure sensor, atmospheric pressure sensor, and right turbocharger inlet pressure sensor, since they use the same ECM supply and wiring architecture.
What other codes might show up alongside 2733?
Check for 262-03 (5 volt sensor supply short to +battery) and 262-04 (5 volt sensor supply short to ground). On some ECM software versions, 2733 will not set if either of those codes is already active, since the 5-volt supply fault is the more fundamental problem.