CAT Engine 273 Fault Code: Turbo Outlet Pressure above normal
Also called Turbo Out Press Above Normal, Turbo Outlet Pressure Above Normal, Turbo Outlet Pressure above Normal, Turbocharger Outlet Pressure Sensor High - Most Severe, Turbocharger Outlet Pressure Sensor High - Most Severe (3), Turbocharger Outlet Pressure Sensor high - most severe (3)
Turbo Outlet Pressure above normal · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Fault code 273 (SPN 102) sets when the CAT ECM sees turbocharger compressor outlet pressure above 200 kpa (29 psi) while the engine is running near low idle, or while the effective fuel limit is low. The ECM flags boost pressure as invalid data and applies a default value of 0 kpa (0 psi), which cuts fuel delivery and causes a noticeable power loss.
Medium severity. The engine keeps running but power is limited because the ECM defaults boost pressure to 0 kpa (0 psi) and restricts fuel delivery. It is not an immediate safety shutdown, but reduced power can affect drivability and productivity, so it should be diagnosed within the work shift.
What does CAT Engine error code 273 mean?
Code 273 relates to the Turbocharger Compressor Outlet Pressure Sensor, which the ECM uses to derive boost pressure. Boost pressure readings control how much fuel the ECM allows during acceleration, similar to how a mechanical governor manages fuel ratio on older engines.
When the ECM sees turbo outlet pressure readings it considers impossible for the current engine speed or fuel limit condition, it decides the sensor signal is invalid. Rather than guess, it defaults the value to 0 kpa (0 psi) and reduces fuel delivery, which limits engine response and power. This is a protective measure to avoid running with bad boost data.
The sensor itself runs on a regulated 5-volt supply from the ECM (J1/P1 pin -63), grounds through pin -6, and sends its signal back on pin -9. Its normal output swings between 0.2 and 4.8 VDC, corresponding to a working pressure range of 33 to 326 kpa (4.8 to 47.3 psi).
What triggers a CAT Engine 273 code?
The ECM logs code 273 when turbocharger outlet pressure reads greater than 200 kpa (29 psi) while one of these is true: engine speed is less than 750 rpm, or the effective fuel limit is at or below 20. In later versions, the trigger is turbo outlet pressure above 200 kpa (29 psi) while engine speed is within 50 rpm of low idle for five seconds, or engine speed is above low idle with the fuel rack at minimum for five seconds. The ECM must have been powered for at least three seconds, and diagnostic codes 262-03, 262-04, 273-03, 273-04, and 273-13 must not be active at the same time.
Common causes of 273
- Damaged, corroded, or loose connectors and wiring at the sensor or ECM
- Leaks in the turbo or intake system, including vacuum leaks, that create abnormal pressure readings
- A faulty or worn turbocharger outlet pressure sensor that needs replacement
- An incorrect sensor installed on the engine (wrong part for the application)
- A problem in the wiring harness, including an open circuit that may not show up at the ECM
- Incorrect supply voltage or incorrect resistance in the sensor circuit
- Incorrect digital sensor duty cycle or frequency
- A defective ECM (less common, but listed as a possible cause)
- Intermittent electrical problems that only show up under certain conditions
- Low fuel and/or oil levels contributing to abnormal readings
How to troubleshoot CAT Engine 273: first checks
- Inspect the sensor connector and related wiring harness for corrosion, damage, loose pins, or chafing, since this is the most commonly listed cause
- Check the sensor supply and ground circuits at the ECM connector (J1/P1 pins -63, -6, and -9) for proper continuity and voltage
- Verify the sensor output voltage falls within the normal 0.2 to 4.8 VDC range across the pressure range of 33 to 326 kpa (4.8 to 47.3 psi)
- Look for intake or turbo system leaks, including vacuum leaks, that could cause abnormal outlet pressure readings
- Confirm the correct sensor part is installed for this engine model, since an incorrect sensor is a listed cause
- Check fuel and oil levels, since low levels are listed as a possible contributing cause
- Pull any related active codes (262-03, 262-04, 273-03, 273-04, 273-13) since their presence blocks 273 from setting and points to a different underlying issue
How the code clears
No separate clearing step is listed beyond repairing the wiring, connector, leak, or sensor issue found during diagnosis. Because the ECM performs an automatic pressure sensor calibration during the first five seconds after the keyswitch is turned ON (as long as the engine is not cranked during that window), a key cycle with the engine left off for that period may be needed after sensor replacement so the ECM can recalibrate. If the engine is cranked before the five second window elapses, the ECM uses the previous calibration data, and a newly installed sensor will need to be calibrated since no previous value exists for it.
Affected models and serial ranges
273 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 fault code 273 mean?
It means the ECM has determined that the turbocharger compressor outlet pressure sensor signal is invalid because the reading exceeded 200 kpa (29 psi) under conditions where that should not happen, such as near low idle. The ECM then defaults boost pressure to 0 kpa (0 psi) and limits fuel to protect the engine.
Why does my CAT engine lose power when code 273 is active?
Because the ECM uses boost pressure to control the air and fuel ratio during acceleration. When it can't trust the turbo outlet pressure signal, it defaults that value to 0 kpa (0 psi) and restricts fuel delivery, which directly reduces engine response and power.
Can a bad connector really cause code 273?
Yes. Damaged, corroded, or loose connectors and wiring are listed as the most common cause across CAT's diagnostic descriptions for this code, affecting both the sensor's supply voltage and its signal line.
Do I need to recalibrate the sensor after replacing it?
Likely yes. The ECM automatically calibrates pressure sensors during the first five seconds after the keyswitch is turned ON, provided the engine is not cranked during that time. A newly installed sensor has no previous calibration value stored, so it needs this calibration window to complete correctly.
Is code 273 the same as code 262?
No, but they're related in the ECM's logic. Codes 262-03 and 262-04 must not be active for code 273 to set, since they represent different circuit failures on a related pressure signal path.
Will code 273 stop my engine from running?
No, but it will limit power. The engine keeps running with reduced fuel delivery and reduced response, since the ECM is operating on a default boost pressure value of 0 kpa (0 psi) instead of a real sensor reading.
What pressure and voltage range should the sensor read normally?
The sensor's normal output is a DC voltage between 0.2 and 4.8 VDC, corresponding to an operating pressure range of 33 to 326 kpa (4.8 to 47.3 psi). Readings well outside this pattern point to a sensor or wiring problem.