CAT Engine 1013 Fault Code: Crankcase Air Pressure Sensor : Voltage Above Normal
Also called Crankcase Air Pressure Sensor - Voltage Above Normal, Crankcase Air Pressure Sensor: Voltage Above Normal, Crankcase Air Pressure Sensor:Voltage Above Normal, Crankcase Pressure Open/Short to +Batt, Crankcase Pressure open/short to +batt, Crankcase Pressure open/short to batt+
Crankcase Air Pressure Sensor : Voltage Above Normal · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
CAT code 1013 (SPN 101 / FMI 3) means the ECM sees crankcase pressure sensor signal voltage above 4.8 VDC for one second after the ECM has been powered for three seconds. The ECM marks crankcase pressure data invalid and disables crankcase pressure monitoring until the fault clears. This code applies to C13, C15, C175, C18, C27, and C32 engines.
Medium severity. This code disables a monitoring function rather than shutting the engine down or forcing a derate on its own. It should still be diagnosed promptly because it removes protection against crankcase pressure problems that can point to internal engine issues.
What does CAT Engine error code 1013 mean?
Code 1013 is triggered by the crankcase air pressure sensor circuit on Caterpillar C13, C15, C175, C18, C27, and C32 engines. The crankcase pressure sensor helps the ECM monitor blow-by and crankcase venting conditions, which can be an early warning sign of ring, piston, or seal wear inside the engine.
When the ECM reads a signal voltage that is too high for this sensor circuit, it can no longer trust the pressure reading. Rather than act on bad data, the ECM logs the fault, flags crankcase pressure as invalid, and turns off the crankcase pressure portion of the engine monitoring system until the problem is fixed.
This is primarily a sensor circuit and wiring issue, not a direct sign of internal engine damage by itself. However, because it disables a protective monitoring feature, it should not be ignored for long periods.
What triggers a CAT Engine 1013 code?
The ECM sets this code when it reads signal voltage greater than 4.8 VDC for one second, provided the ECM has already been powered for three seconds and diagnostic codes 262-03 and 262-04 are not currently active.
Common causes of 1013
- Damaged, corroded, or loose connectors and wiring in the crankcase pressure sensor circuit
- A problem within the wiring harness itself, such as chafing or a short to battery voltage
- A faulty or failed crankcase pressure sensor that needs replacement
- A faulty ECM (less common, but listed as a possible cause)
- Vacuum leak affecting the crankcase pressure reading
- Low oil level
- Low fuel level
- Intermittent connection problems that only show up under vibration or temperature changes
How to troubleshoot CAT Engine 1013: first checks
- Inspect the crankcase pressure sensor connector and wiring harness for corrosion, moisture, pinched wires, or damaged pins. Terminal 1 carries supply voltage, terminal 2 is sensor return, and terminal 3 carries the sensor signal.
- Check engine oil level and fuel level, since both are listed as possible causes for this code on some models.
- Look for vacuum leaks in lines or fittings connected to the crankcase pressure sensing system.
- With the engine off for at least five seconds, cycle the key to allow the ECM's automatic sensor calibration to run, then recheck for the active code.
- Use a diagnostic scan tool to confirm whether codes 262-03 or 262-04 are active, since those must be inactive for 1013 to set, and their presence changes the diagnostic path.
- If wiring and connectors check out, test or swap the crankcase pressure sensor itself before condemning the ECM.
How the code clears
No separate reset procedure is listed for this code beyond correcting the underlying wiring, connector, sensor, oil level, fuel level, or vacuum leak issue. Once the fault condition is resolved and the ECM completes its automatic sensor calibration during an engine-off period, the code should stop being active. Confirm with a diagnostic scan tool that the code is no longer active and that crankcase pressure monitoring has resumed.
Affected models and serial ranges
1013 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 1013 mean?
It means the ECM detected crankcase air pressure sensor signal voltage above 4.8 VDC for one second, which is outside the acceptable range. The ECM then treats the crankcase pressure reading as invalid and disables that part of the engine monitoring system.
Is CAT fault code 1013 serious?
It is not an immediate shutdown code, but it disables crankcase pressure monitoring, which is a protective feature. It should be diagnosed and repaired in a reasonable timeframe rather than ignored.
What usually causes code 1013?
The most common causes are damaged or corroded wiring and connectors, a faulty crankcase pressure sensor, or a harness problem. Less commonly it can be caused by low oil level, low fuel level, a vacuum leak, or a faulty ECM.
Which CAT engines can show code 1013?
This code applies to the C13, C15, C175, C18, C27, and C32 engine families.
Can low oil or fuel level actually trigger this sensor code?
Yes, low oil level and low fuel level are both listed as possible causes for this fault, likely because they affect crankcase venting or pressure conditions that the sensor monitors.
Will fixing the wiring clear the code by itself?
Repairing the wiring, connector, or sensor issue should stop the fault condition from recurring. There is no separate manual reset procedure listed; the ECM's automatic sensor calibration, which runs when the engine has been off for at least five seconds, helps confirm the fix on the next power-up.
What other codes are related to this one?
Diagnostic codes 262-03 and 262-04 are directly referenced: code 1013 will not set if either of those codes is already active, so technicians should check those first when troubleshooting.