Camshaft Position Sensor (Secondary) - Data Erratic, Intermittent, or Incorrect
What does CAT-CID342-FMI2 mean?
The CAT-CID342-FMI2 (Caterpillar) diesel fault code means: Camshaft Position Sensor (Secondary) - Data Erratic, Intermittent, or Incorrect. This is a serious severity code.
Common Symptoms
- Intermittent Check Engine Light
- Erratic or fluctuating signal on CAT ET
- Possible stumble or momentary power loss
Probable Causes (Ranked by Likelihood)
- Intermittent wiring fault from chafe or loose pin Very Likely
- Failing sensor producing noise Likely
- EMI or ground noise or bad ECM ground Possible
Step-by-Step Diagnostic Procedure
Wiggle-test the harness and connector while watching live data on CAT ET for dropouts.
Back-probe the signal pin and measure during operation; erratic readings confirm the circuit or sensor.
Inspect connector pin tension and replace the sensor if harness checks good.
Frequently Asked Questions
What does CAT code CID342-FMI2 mean?
CAT code CID342-FMI2 (Camshaft Position Sensor (Secondary) - Data Erratic, Intermittent, or Incorrect) is a serious-severity fault on Caterpillar on-highway diesel engines. CID 342 is the Camshaft Position Sensor (Secondary), measuring secondary camshaft speed and timing signal. FMI 2 (Data Erratic, Intermittent, or Incorrect) indicates the specific fault mode. Use CAT ET to confirm before replacing parts. Diagnose with CAT ET (Electronic Technician) software.
Can I drive my truck with CAT code CID342-FMI2?
Short distances may be acceptable, but running long with this fault risks progressive damage or forced derate. Address promptly.
How much does it cost to fix CAT CID342-FMI2?
Typical repair is $200-$800. Sensor / wiring fixes fall at the low end; injector, HEUI pump, turbo, or aftertreatment work falls at the high end. CAT dealer labor often requires CAT ET for calibration and parameter programming.