CAT Engine 178513 Fault Code: Intake Manifold Pressure Sensor : Calibration Required
Also called Engine Intake Manifold #1 Absolute Pressure : Calibration Required, Engine Intake Manifold #1 Absolute Pressure : Out of Calibration, Intake Manifold Pressure Sensor - Calibration Required, Intake Manifold Pressure Sensor : Out of Calibration, Intake Manifold Pressure Sensor: Calibration Required, Intake Manifold Pressure Sensor:Calibration Required
Intake Manifold Pressure Sensor : Calibration Required · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
CAT code 178513, also shown as SPN 3563 / FMI 13 or 3563-13 (1785-13), means the ECM could not calibrate the intake manifold #1 absolute pressure sensor because its signal voltage was not close enough to the reference or barometric pressure sensor value. It affects C13, C15, C18, C27, and C32 engines and points to a wiring, connector, debris, or sensor problem rather than a dangerous running condition by itself.
Medium severity. This is a calibration fault, not a direct overpressure or overheat warning. It should be diagnosed within the shift because the ECM may fall back to a stored offset value, which can affect boost-related engine performance and other pressure-based calculations until corrected.
What does CAT Engine error code 178513 mean?
Code 178513 (SPN 3563 / FMI 13) relates to the intake manifold #1 absolute pressure sensor on CAT C13, C15, C18, C27, and C32 engines. This sensor tells the ECM how much pressure is in the intake manifold so the engine can manage fueling and boost correctly.
During each key on event of at least 2 seconds, the ECM checks the signal voltage from each pressure sensor against a reference voltage. If the signal is close enough, the ECM automatically adjusts it in a process called automatic sensor calibration. If it is not close enough, the ECM cannot calibrate the sensor and sets this fault code instead.
A more detailed version of this check compares the intake manifold pressure sensor to the barometric pressure sensor. The pressure offset found during this comparison must be within 15 kPa (2.2 psi) of the barometric sensor reading. If the offset falls outside that range, the fault is logged as 3563-13 (1785-13). If the ECM cannot complete this comparison, it falls back on a previously stored offset value.
What triggers a CAT Engine 178513 code?
The ECM evaluates sensor signal voltage during each key on event lasting at least 2 seconds. Separately, the ECM checks the intake manifold pressure sensor signal against the barometric pressure sensor beginning 12 seconds after the keyswitch is turned OFF, and the key must stay OFF for a further 2 seconds for this check to complete. The pressure offset found must be within 15 kPa (2.2 psi) of the barometric sensor signal or the code is logged.
Common causes of 178513
- Faulty or failed intake manifold pressure sensor
- Sensor port blocked by debris
- Damaged, corroded, or moisture-affected connectors or wiring
- General harness problem in the sensor circuit
- Intermittent connection or wiring fault
- Existing diagnostic trouble codes affecting related circuits that should be checked first
How to troubleshoot CAT Engine 178513: first checks
- Check for any other active or logged diagnostic trouble codes before working on this one, since related faults can affect the pressure sensor circuit
- Inspect the suspect sensor connector for damage, corrosion, or moisture and clean or dry it as needed
- Check the sensor port for debris or blockage that could affect the pressure reading
- Inspect the wiring harness between the ECM and the sensor for chafing, pinches, or loose pins
- Verify the connector pins are fully seated and making good contact, with no bent or pushed-back terminals
- If wiring and connectors check out, test or replace the intake manifold pressure sensor itself
How the code clears
No separate clearing step is listed beyond fixing the root cause. Once the wiring, connector, debris, or sensor issue is corrected, the ECM should be able to complete automatic sensor calibration on a subsequent key on event or during the key OFF comparison cycle, which clears the fault. No manual reset procedure is described.
Affected models and serial ranges
178513 appears in our records across 5 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 |
| 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 178513 mean?
It means the ECM tried to calibrate the intake manifold #1 absolute pressure sensor and could not, because the sensor's signal voltage was not close enough to the reference voltage or to the barometric pressure sensor reading. It is also identified as SPN 3563 / FMI 13 or 3563-13 (1785-13).
Is code 178513 safe to keep driving or working with?
It is not an immediate stop-now warning, but it should not be ignored. Since the ECM may be using a stored offset value instead of a live calibrated reading, boost and fueling calculations could be slightly off. Get it diagnosed within the same shift if possible.
What usually causes this fault?
The most common causes are a blocked sensor port, damaged or corroded wiring and connectors, moisture in the connector, an intermittent harness fault, or a failed sensor itself.
Which CAT engines does this code affect?
This fault code applies to C13, C15, C18, C27, and C32 engines.
How does the ECM decide to set this code?
During key on events of at least 2 seconds, the ECM compares the sensor's signal voltage to a reference voltage. It also runs a check starting 12 seconds after key OFF, requiring the key to stay OFF for 2 seconds more, comparing the intake manifold pressure sensor to the barometric pressure sensor. If the offset is outside 15 kPa (2.2 psi), the code sets.
Do I need to reset the code after fixing the problem?
No separate reset procedure is listed. Once the underlying wiring, connector, or sensor issue is repaired, the ECM should recalibrate automatically during a normal key cycle and the code should clear on its own.
Can debris really cause a calibration fault like this?
Yes. If the sensor port is blocked by debris, the sensor cannot read true manifold pressure, which throws off the calibration comparison and triggers the fault even if the sensor and wiring are otherwise fine.