What is Komatsu PC220-8 Fault Code E-13?

Komatsu PC220-8 fault code E-13 indicates an Engine Pre-Heater Relay Circuit malfunction, specifically detecting an abnormality in the glow plug relay control circuit within the engine control system. This diagnostic trouble code (DTC) signals that the Engine Control Module (ECM) has identified either an open circuit, short circuit, or improper voltage reading in the pre-heating system that aids cold-start performance.

This code is critical for the PC220-8's Komatsu SAA6D107E-1 engine because the pre-heater system ensures proper combustion chamber temperatures during cold starts, particularly in temperatures below 50°F (10°C). When this circuit malfunctions, the engine may experience hard starting, excessive white smoke during startup, and increased wear on internal components due to incomplete fuel combustion during the warm-up phase.

Common Symptoms

When fault code E-13 is active on your Komatsu PC220-8, operators typically experience:

• Extended cranking time during cold starts, especially in cooler weather conditions
• Glow plug indicator light remaining illuminated longer than normal or failing to activate
• Excessive white or gray smoke from the exhaust during initial startup
• Rough idle for the first 2-5 minutes of operation until the engine reaches operating temperature
• Monitor panel warning displaying the E-13 code with possible derate mode activation in extreme cases

Potential Causes

The most common technical reasons for code E-13 on used PC220-8 excavators include:

• Failed glow plug relay located in the engine compartment relay box (common failure point after 5,000+ operating hours)
• Corroded or damaged wiring harness connections at the relay socket, particularly due to moisture intrusion near the battery box area
• Faulty ECM output circuit for relay control, though less common than relay or wiring issues
• Blown fuse in the pre-heater circuit (typically a 30A fuse in the main power distribution box)
• Damaged connector pins at the C1 or C2 ECM connectors showing signs of heat damage or corrosion
• Intermittent ground connection at the relay mounting point due to paint buildup or rust

How to Troubleshoot and Fix Code E-13

Step 1: Visual Inspection Begin by locating the glow plug relay in the engine compartment relay box (right side, near the battery). Inspect all connector terminals for corrosion, heat damage, or bent pins. Check the wiring harness from the relay to the ECM for chafing points, especially where it passes near the air conditioning compressor bracket—a known wear point on used PC220-8 models.

Step 2: Electrical Testing Using a digital multimeter, check the 30A fuse in the main power distribution box for continuity. With the key in the ON position (engine off), measure voltage at the relay coil terminals—you should see battery voltage (24V) during the pre-heat cycle. If voltage is absent, trace back to the ECM connector C1, pin 22 for output signal integrity.

Step 3: Relay and Component Verification Remove the glow plug relay and perform a bench test or substitute with a known-good relay of identical specifications (Komatsu part #600-815-8940 or equivalent). If the code clears, replace the relay. If the code persists, use Komatsu diagnostic software (KOMTRAX Plus) to monitor ECM output commands and verify the ECM is sending proper control signals. For used excavators, always clean all ground connections with a wire brush and apply dielectric grease to prevent future corrosion-related failures.

Professional Disclaimer: This guide provides general diagnostic procedures for informational purposes. Always consult the official Komatsu PC220-8 service manual and consider professional assessment by a certified Komatsu technician for complex electrical diagnostics or ECM-related repairs.