KUKA KSS00406 Position Deviation Error – Causes, Symptoms & How to Fix

Error Code Overview

• Error Code: KSS00406
• Category: Servo / Motion Control
• Severity: High
• System: KRC4 / KSP Drives
• Impact: axis disabled, robot motion halted, potential safety risk

Quick Fix for KUKA KSS00406

If KUKA KSS00406 Position Deviation Error appears:

• Stop all robot motion immediately.
• Reset the KRC4 controller and clear active faults.
• Verify the affected axis is free from obstruction.
• Reduce speed and acceleration override settings.
• Inspect servo motor, encoder, and resolver wiring.
• Power cycle the affected KSP drive if necessary.

⚠️ Safety Note: Always power down the robot before inspecting motors, brakes, or drive connections.

What Is KUKA KSS00406 Position Deviation Error?

KUKA KSS00406 Position Deviation Error occurs when the robot’s actual axis position differs beyond the permitted tolerance from the commanded target position.

KUKA controllers continuously compare:

• commanded servo position,
• real encoder/resolver feedback,
• calculated motion trajectory.

If the deviation becomes too large, the controller triggers KSS00406 to prevent uncontrolled motion or mechanical damage.

Th is fault is also commonly referred to as:

• KUKA axis following error
• ervo tracking deviation
• osition lag alarm.

Common Symptoms of KUKA KSS00406

Typical symptoms include:

• axis stops suddenly during motion
• Robot refuses to continue program execution
• SmartHMI displays KSS00406 alarm
• Red LED appearson affected KSP module
• Robot movement becomes jerky or unstable before shutdown

Common Causes of KUKA KSS00406

Mechanical Resistance or Obstruction

Mechanical drag is one of the most common causes of position deviation.

Th is includes:

• gearbox backlash,
• eized bearings,
• coupling slippage,
• joint obstruction,
• rake drag/failure.

If the motor cannot physically keep up with commanded motion, deviation increases rapidly.

Servo Motor or Drive Fault

If the servo system underperforms, the axis may lag behind target position.

Potential causes include:

• weak servo motor output,
• KSP drive instability,
• current loop faults,
• intermittent drive shutdowns.

Encoder or Resolver Feedback Issues

The KRC dependson accurate feedback for axis tracking.

KSS00406 may occur if:

• encoder/resolver cable is damaged,
• ignal noise distorts feedback,
• feedback connector is loose,
• KSP feedback circuit is faulty.

Excessive Payload or Torque Load

Overloading the robot can create servo lag.

Typical triggers include:

• ayload exceeds rating,
• incorrect payload setup,
• udden torque spikes,
• aggressive acceleration/deceleration.

Parameter or Firmware Mismatch

Incorrect system parameters can distort motion calculations.

Examples include:

• mismatched KRC/KSP firmware,
• corrupted drive configuration,
• invalid axis tuning values,
• incorrect mastering/axis calibration data.

Recommended Replacement Parts

⚠️ Compatibility Tip: Always verify robot serial number, axis number, and KSS version before ordering replacement parts.

How to Repair KUKA KSS00406

Step 1 – Inspect Mechanical axis

Check for:

• inding joints,
• gearbox stiffness,
• coupling looseness,
• rake drag.

Step 2 – Check Servo Drive Status

Inspect KSP LEDs and diagnostics.

If needed:

• wap with known-good drive for testing.

Step 3 – Test Feedback Devices

Inspect encoder/resolver:

• cable continuity,
• connector seating,
• ignal integrity.

Step 4 – Run Reduced-Load Motion Test

Temporarily:

• lower override speed,
• reduce acceleration,
• remove payload if possible.

Then retest axis movement.

Step 5 – Verify Parameters/Firmware

Check:

• firmware compatibility,
• drive configuration,
• axis tuning values.

Step 6 – Replace Faulty Components

If hardware failure is confirmed:

• replace motor,
• replace KSP drive,
• replace encoder/resolver hardware.

When to Stop Operation Immediately

Stop operating the robot immediately if:

• KSS00406 occurs repeatedlyon the same axis,
• motion becomes unstable or jerky,
• loud mechanical noise accompanies the fault,
• axis drifts or overshoots unexpectedly.

Continued operation may cause:

• gearbox damage,
• rake failure,
• uncontrolled motion events.

Pro Diagnostic Tip for KUKA KSS00406

Navigate to:

SmartHMI → axis Diagnostics → Position Feedback

Compare:

• commanded position,
• actual position,
• torque load.

Watching deviation grow in real time helps identify whether the root cause is:

• mechanical drag,
• feedback loss,
• ervo underperformance.

How to Prevent KUKA KSS00406

To reduce future KSS00406 faults:

• inspect gearboxes and joints regularly,
• maintain correct payload calibration,
• route feedback cables away from noise sources,
• keep control cabinet cooling clean and effective,
• replace aging servo hardware proactively.

Related KUKA Errors

⚠️ Technical Note: Position deviation is frequently a secondary effect of:

• KSS00402Resolver Failure - Feedback loss causing servo instability
• KSS01312 Brake Fault - Brake drag/hold issues affecting motion
• KSS00021 Bus Communication Error - Drive communication failure
• KSS01444 Servo Fault - General motion/servo abnormality

FAQ About KUKA KSS00406

What does KUKA KSS00406 mean?

It indicates that the actual axis position deviates beyond allowed tolerance, causing the controller to stop motion.

Can the robot operate with a position deviation error?

No. Motion is blocked until the deviation is resolved.

How do I fix KUKA position deviation errors?

Inspect mechanical axes, check motors and feedback devices, reduce load, and replace faulty components if needed.

Can payload or acceleration cause KSS00406?

Yes. Excessive payload or sudden torque spikes can trigger position deviation errors.

Which step should be checked first if KSS00406 occurs?

Start with mechanical axis inspection → motor/drive LEDs → encoder/resolver feedback → firmware/parameter check.