CAT Engine 15893 Fault Code: Turbo Inlet Air Pressure Sensor Open/Short to +Batt
Also called Turbo Inlet Air Pressure Sensor Voltage Above Normal, Turbo Inlet Air Pressure Sensor open/shrt to +bat, Turbocharger Inlet Air Pressure Sensor : Voltage Above Normal
Turbo Inlet Air Pressure Sensor Open/Short to +Batt · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Code 15893 sets when the ECM sees signal voltage from the turbocharger inlet air pressure sensor above normal, generally above 4.95 volts DC. On C27 and C32 engines the ECM flags the turbo inlet pressure reading as invalid, substitutes a default value, and logs the code. Depending on the specific control strategy this may trigger a derate and warning, or may have no noticeable performance effect at all.
Medium severity. This code alone usually does not stop the engine, but on some versions it forces a default air inlet restriction value and a 10% engine derate with a dash warning. Treat it as a diagnose-this-shift item, sooner if a derate or warning message appears.
What does CAT Engine error code 15893 mean?
Code 15893 relates to the turbocharger inlet air pressure sensor circuit on C27 and C32 engines. This sensor tells the ECM how much air pressure is present at the turbo inlet, which the ECM uses to calculate air inlet restriction and manage engine performance and emissions.
When the ECM sees the signal voltage from this sensor climb above normal, above 4.95 volts DC in the documented condition, it treats the reading as invalid. Rather than trust a bad number, the ECM flags the turbo inlet pressure data as invalid and substitutes a default value so the engine keeps running.
In some versions of this fault, the ECM defaults the air inlet restriction to 14 kPa (2.0 psi) and applies a 10% engine derate along with a warning on the control panel display. In other documented versions, there are no performance effects at all, just a logged code. Which behavior you see depends on the specific ECM software and engine configuration.
What triggers a CAT Engine 15893 code?
The ECM sets this code when it detects signal voltage from the turbo inlet air pressure sensor above normal, specifically above 4.95 volts DC in one documented version, sustained for at least one second. The ECM must have been powered for at least three seconds, or in another version the engine must have been running for at least three minutes, before the code will log. One version also requires that diagnostic code 0168-01 not be active at the same time.
Common causes of 15893
- Damaged, corroded, or loose connectors and wiring at the sensor or ECM
- A problem within the wiring harness, including chafed or pinched sections
- An intermittent connection issue that only shows up under vibration or temperature change
- A faulty or failing turbocharger inlet air pressure sensor
- A faulty ECM that is not reading or producing signal correctly
How to troubleshoot CAT Engine 15893: first checks
- Inspect the sensor connector and ECM connector for corrosion, moisture, or loose pins before touching anything else
- Trace the harness between the sensor and ECM looking for chafe points, pinches, or abrasion, especially near moving parts or sharp edges
- Check the sensor's signal wire for a short to a high-voltage source, since the fault condition is voltage reading too high, not too low
- Wiggle-test the harness and connectors with the engine running or key on to try to reproduce an intermittent fault
- Verify the sensor is receiving correct supply voltage from the ECM and that the signal circuit is not shorted to a battery or power source
- If wiring and connectors check out, test or swap the turbo inlet air pressure sensor itself before condemning the ECM
How the code clears
No separate clearing step is listed beyond repairing the fault. Once the wiring, connector, or sensor issue is corrected and the voltage returns to a normal range, the ECM should stop logging the active fault. If a stored code remains after the repair, clear it with a diagnostic tool per your normal shop procedure and confirm it does not return during a test run.
Affected models and serial ranges
15893 appears in our records across 2 CAT Engine models. Match your machine by model and serial number.
| Model | Serial ranges |
|---|---|
| C27 | Serial range not listed in source records |
| C32 | Serial range not listed in source records |
Frequently asked questions
What does CAT code 15893 mean?
It means the ECM detected signal voltage from the turbocharger inlet air pressure sensor that is above normal, above 4.95 volts DC in the documented threshold. The ECM treats the pressure reading as invalid and substitutes a default value.
Will code 15893 cause a derate or shut down my engine?
It depends on the version. Some documented behavior includes a default air inlet restriction value of 14 kPa (2.0 psi) and a 10% engine derate with a dashboard warning. Other documented versions show no performance effect, just a logged code.
What usually causes this code?
The most common causes are damaged or corroded connectors, wiring problems in the harness, intermittent connections, a faulty sensor, or in less common cases a faulty ECM.
Is this an electrical problem or a mechanical one?
It is an electrical signal circuit issue. The turbo inlet air pressure sensor, its wiring, and its connectors are the primary suspects, not the turbocharger itself.
Can I keep operating the machine with this code active?
If no derate or warning is present, the engine may run normally with just the code logged. If a derate and warning message appear, get the machine into the shop soon since air inlet pressure data is being defaulted rather than measured.
Does this code affect the throttle position sensor too?
No. Throttle position sensor detail appears in some documentation for related codes, but code 15893 itself is specific to the turbocharger inlet air pressure sensor circuit.
How do I confirm the sensor itself is bad versus the wiring?
Check connectors and trace the harness for damage first, since wiring and connector issues are the most frequently listed causes. If wiring checks out clean, test or replace the sensor before replacing the ECM.