What is Volvo EC290B Fault Code 128 PID 1105?

Fault Code 128 PID 1105 on the Volvo EC290B excavator indicates an open circuit or abnormal voltage detected in the Intake Air Heater (Grid Heater) control circuit. This diagnostic trouble code (DTC) is triggered when the Engine Control Module (ECM) detects a malfunction in the electrical system that powers the intake manifold heater used during cold starts.

The Intake Air Heater is critical for diesel combustion efficiency in cold weather conditions, pre-heating incoming air to ensure proper atomization of fuel and smooth engine starting. On the Volvo EC290B, which uses a D6E or D7E engine platform, this system directly affects cold-start performance and initial engine operation. When PID 1105 registers a fault, the ECM logs the code and may disable the grid heater function entirely to prevent electrical damage, potentially leading to hard starts in freezing conditions.

Common Symptoms

• Hard starting or extended cranking time in cold weather (below 40°F/5°C)
• Check Engine Light (CEL) or malfunction indicator illuminated on the dash
• White or gray exhaust smoke during initial startup due to incomplete combustion
• Rough idle for the first few minutes after a cold start
• Reduced engine performance until operating temperature is reached

Potential Causes

The most common technical failures triggering Code 128 PID 1105 on used EC290B excavators include:

• Open circuit in the grid heater relay or control wiring harness (common wear point near the intake manifold)
• Failed Intake Air Heater element due to age-related burnout or thermal cycling damage
• Corroded or loose electrical connectors at the heater assembly or ECM connection points
• Damaged wiring harness from rubbing against the engine block or hydraulic lines (known issue on older EC290B models)
• Faulty ECM relay controlling grid heater power distribution
• Blown fuse in the intake heater power circuit (often overlooked during initial diagnostics)

How to Troubleshoot and Fix Code 128 PID 1105

Step 1: Visual Inspection and Connection Check Begin by inspecting the intake air heater wiring harness for visible damage, especially where it routes near hot engine components. Check all electrical connectors at the heater element and relay for corrosion, bent pins, or moisture intrusion—common issues in used excavators exposed to harsh environments.

Step 2: Electrical Testing Using a digital multimeter, measure resistance across the grid heater element terminals with the connector disconnected and ignition off. Typical resistance should read between 0.5-2.0 ohms (consult service manual for exact specifications). An infinite reading indicates an open circuit in the heater element itself. Next, check for battery voltage (12V) at the heater supply wire with ignition on—no voltage indicates a relay or fuse failure.

Step 3: Relay and Fuse Verification Locate the intake heater relay in the main fuse box and test it by swapping with an identical relay, or bench-test using a relay tester. Check the associated fuse rating (typically 30-50A) for continuity. On used machines, corrosion inside the fuse box is common and may cause intermittent faults.

Step 4: Diagnostic Software Scan Connect Volvo VCADS (Volvo Construction Assistance Diagnostic Software) or equivalent scan tool to read live data from the ECM. Monitor the grid heater command status during cranking—if the ECM commands activation but no current flow is detected, the issue lies in the physical circuit rather than ECM logic.

Step 5: Component Replacement Replace the intake air heater element if resistance testing confirms failure. For used excavators, always replace associated connectors and terminal ends to prevent recurring faults from worn contacts. Clear codes with diagnostic software and perform a cold-start test to verify repair.

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Disclaimer: This guide provides general troubleshooting steps for educational purposes. Always consult the official Volvo service manual for your specific machine serial number and software version. If you're unfamiliar with high-current electrical systems or diagnostic procedures, seek assistance from a certified Volvo technician to avoid equipment damage or personal injury.