Applicable Systems
EMCP 4.2
Symptoms
The EMCP 4.2 displays fault 164-3 indicating the Injector Actuation Pressure circuit voltage is above normal or shorted to a high source. The engine may derate or shut down to protect the fuel injection system.
Possible Causes
- Injector Actuation Pressure sensor signal wire shorted to battery positive
- Sensor internal failure producing high voltage output
- ECM connector corrosion causing cross-circuit
- Wiring harness chafing exposing conductor to power source
Troubleshooting Steps
- Step 1: Read active fault codes on EMCP display panel
Fault 164-3 shown as active with engine status - Step 2: Disconnect IAP sensor connector and measure signal pin voltage
Voltage should be 0V with sensor disconnected; if battery voltage present, wiring is shorted - Step 3: Inspect wiring harness from IAP sensor to ECM for chafing or damage
No exposed conductors or insulation damage found - Step 4: Replace IAP sensor if wiring checks good but fault persists after reconnection
Fault clears after sensor replacement and key cycle
How to Reset
To reset: 1) Repair the short circuit or replace the faulty sensor. 2) Press FAULT RESET on EMCP. 3) Press AUTO. Caution: Do not reset without fixing the root cause.
Common Replacement Parts
- 164-0026: Caterpillar Injector Actuation Pressure Sensor (Match to engine model and serial number)
Frequently Asked Questions
- Q: What is the normal operating voltage for the IAP sensor on Cat engines?
The IAP sensor typically operates at 0.5-4.5 VDC. A reading above 4.5 VDC triggers FMI 3 (voltage above normal).
- Q: Can I drive the generator with fault 164-3?
The engine may derate to protect the injection system. Continued operation can cause injector damage. Investigate immediately.
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Source: Caterpillar EMCP 4.2 Operation & Maintenance Manual (LERMPMM), caterpillarfaultcodes.com CID-FMI Reference
Category: Generator
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