Welcome to the next level of machine mastery. These five additional Bobcat fault codes offer insights into system inconsistencies, hidden malfunctions, and preventive maintenance opportunities. Let’s break each one down so you can stay one step ahead in the field.

1. M2721 – Radiator Cooling Fan Speed Low

What It Means: The fan is rotating below its expected speed, leading to potential overheating.

Troubleshooting Tips:

• Inspect belt tension, fan bearings, and the drive motor.
• Test fan speed sensor output against spec.
• Check for obstructions in airflow or dirty radiator fins.

Prevention Advice: Clean radiator and fan blades weekly. Lubricate moving parts per the maintenance schedule.

2. M3505 – Travel Motor Speed Mismatch

What It Means: Left and right travel motors are moving at inconsistent speeds.

Troubleshooting Tips:

• Verify travel speed sensors are functioning.
• Inspect hydraulic hoses for pressure loss.
• Recalibrate motor sensors using diagnostic software.

Prevention Advice: Regularly check track tension and clean undercarriage components.

3. M1028 – Ignition Relay Feedback Fault

What It Means: The ignition relay signal is not returning as expected to the ECU.

Troubleshooting Tips:

• Check relay coil resistance and voltage.
• Inspect fuse and ignition switch circuits.
• Replace relay or faulty harness sections.

Prevention Advice: Keep the electrical system dry and clean. Inspect wiring during seasonal service.

4. M0515 – Glow Plug Activation Time Exceeded

What It Means: The glow plugs are staying on longer than normal, possibly due to sensor error or ECU misread.

Troubleshooting Tips:

• Check engine coolant temperature sensor.
• Inspect glow plug relay for sticking.
• Reflash or replace ECU if timing remains off.

Prevention Advice: Always allow proper cooldown. Test glow plug system prior to winter use.

5. M2123 – Boom Cylinder Position Sensor Fault

What It Means: Inaccurate or missing data from the boom cylinder sensor.

Troubleshooting Tips:

• Visually inspect wiring and sensor placement.
• Compare actual boom movement to sensor data in diagnostics.
• Replace sensor if output is inconsistent.

Prevention Advice: Avoid impact loading the boom. Keep hydraulic lines and sensors clean.

Stay Smart, Stay Productive

Every code is an opportunity—not just a warning. By acting early and using reliable diagnostic techniques, you reduce breakdown risks and extend your machine’s lifespan. More codes, fewer surprises—that’s the Bobcat advantage.