Caterpillar Excavator Fault Code 267-4: Meaning, Symptoms & Fix

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What is Caterpillar Fault Code 267-4?

Caterpillar Fault Code 267-4 indicates a low voltage condition on the Throttle Position Sensor (TPS) circuit, specifically signaling that the signal voltage has dropped below the acceptable threshold defined by the ECM (Engine Control Module).

This fault belongs to the Component Identifier (CID) 267, which monitors the throttle position input signal. The Failure Mode Identifier (FMI) 4 confirms a "Voltage Below Normal" reading on that circuit.

On Caterpillar machines, accurate throttle position data is critical for proper fuel delivery, engine response, and hydraulic system performance. When this signal is corrupted or lost, the ECM cannot correctly interpret operator throttle inputs, directly impacting machine productivity and safety.

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Common Symptoms

When Fault Code 267-4 is active, operators and technicians may observe the following:

• Engine derate or power limitation, with the machine refusing to reach full RPM
• Erratic or unresponsive throttle behavior, including hesitation during acceleration
• Active warning lamp illuminated on the operator display panel
• Reduced hydraulic performance, as engine speed directly governs hydraulic flow output
• Intermittent stalling or difficulty maintaining a steady idle

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Potential Causes

Several technical factors can trigger a 267-4 code, particularly on used or high-hour excavators:

• Failed or worn Throttle Position Sensor — common on machines with 5,000+ hours
• Damaged wiring harness — chafing, cuts, or pinch points near the throttle assembly or firewall routing
• Corroded or loose connector pins at the sensor or ECM connector block
• Short to ground within the signal wire of the TPS circuit
• ECM internal fault — less common but possible on older machines with moisture ingress history

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How to Troubleshoot and Fix Code 267-4

Step 1 — Preliminary Visual Inspection Begin with a thorough inspection of the TPS wiring harness. On used excavators, pay close attention to known rub points near metal brackets, the engine firewall, and cable tie locations. Look for fraying, heat damage, or corrosion on connector pins. Clean connectors with electrical contact cleaner before proceeding.

Step 2 — Voltage and Resistance Testing Using a digital multimeter, backprobe the TPS signal wire at the sensor connector. With the key ON (engine off), the signal voltage should typically read between 0.5V and 4.5V depending on throttle position. A reading below 0.3V confirms the low voltage fault. Check supply voltage (5V reference) and ground integrity at the sensor connector as well.

Step 3 — Diagnostic Software Verification Connect Caterpillar ET (Electronic Technician) software to monitor live TPS data and confirm the fault is active. Use ET to perform a wiggle test on the harness while monitoring signal voltage for intermittent drops — a strong indicator of a harness fault rather than sensor failure.

Step 4 — Component Replacement If wiring and connectors test satisfactory, replace the Throttle Position Sensor with a genuine or OEM-equivalent part. Clear fault codes using Cat ET and retest under operating conditions.

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Disclaimer: This guide is intended for informational purposes and qualified technicians. Always consult a certified Caterpillar dealer or licensed heavy equipment mechanic before performing repairs. Improper diagnosis or repair can result in equipment damage, safety hazards, or voided warranties.