What is Doosan DX215-9C Fault Code E520687-12 (P160A)?

Fault Code E520687-12 (P160A) on the Doosan DX215-9C excavator indicates a malfunction in the Engine Intake Air Heater Circuit, specifically a short circuit to ground or abnormal voltage detected in the intake air heater relay control system. This diagnostic trouble code (DTC) is generated by the Electronic Control Module (ECM) when it detects an electrical fault in the circuit that controls the intake air heater, which is critical for cold-start performance in diesel engines.

The intake air heater (also called a grid heater or intake manifold heater) preheats incoming air during cold weather starts, ensuring proper combustion and reducing white smoke during engine warm-up. When this circuit malfunctions, the DX215-9C's engine management system flags the fault to prevent potential starting issues or component damage. This code is particularly important for used excavators operating in cold climates, as repeated failed starts can damage the starter motor and drain batteries prematurely.

Common Symptoms

• Check Engine Light (CEL) or engine diagnostic warning illuminated on the instrument cluster
• Difficult cold starts or extended cranking time, especially in temperatures below 40°F (4°C)
• Excessive white or gray smoke during initial startup that persists longer than normal
• Rough idle for the first few minutes after cold start until engine reaches operating temperature
• Reduced engine performance during warm-up phase with possible hesitation under load

Potential Causes

The most common technical reasons for Code E520687-12 appearing on used DX215-9C excavators include:

• Damaged or corroded wiring harness in the intake air heater circuit, particularly at connection points near the engine block where vibration and heat cause insulation breakdown
• Failed intake air heater relay located in the main electrical junction box, often due to contact wear or coil failure
• Shorted intake air heater element itself, which draws excessive current and triggers ground fault detection
• Corroded or loose electrical connectors at the heater assembly or relay socket—common in machines exposed to moisture or stored outdoors
• ECM internal fault in the heater control driver circuit (less common but possible in higher-hour machines)
• Damaged wiring from previous repairs or modifications, especially near the air intake system where harnesses may have been disturbed

How to Troubleshoot and Fix Code E520687-12 (P160A)

Step 1: Initial Inspection and Code Verification Connect a Doosan diagnostic laptop with G-Scan or compatible software to verify the fault code is active and check for additional related codes. Perform a visual inspection of the intake air heater assembly and all associated wiring harnesses from the ECM to the heater relay and heater element. On used excavators, pay special attention to harness routing near sharp edges, hot exhaust components, and areas with visible wear or melted insulation.

Step 2: Test the Intake Air Heater Relay Locate the intake air heater relay in the main electrical junction box (typically under the operator cab or near the battery compartment). Remove the relay and test it using a multimeter. Check for continuity between the coil terminals (should read 70-100 ohms typically) and verify the contacts close when 12V is applied to the coil. Replace the relay if it fails either test. For used machines, inspect the relay socket for corrosion, pushed-back pins, or evidence of overheating.

Step 3: Check Wiring Harness and Connectors Using a digital multimeter, perform a continuity test from the ECM connector (pin corresponding to heater control output per service manual) to the relay coil terminal. Resistance should be less than 5 ohms. Check for shorts to ground by measuring resistance between the control wire and chassis ground with the circuit disconnected (should read infinite/open). Inspect all connectors for corrosion, moisture intrusion, or bent pins—common issues in older excavators. Apply dielectric grease to cleaned connections during reassembly.

Step 4: Test the Intake Air Heater Element Disconnect the heater element connector and measure resistance across the heater terminals. Typical values range from 0.5 to 2.0 ohms depending on heater design (consult service manual for exact specification). If resistance is significantly higher, the element is open and requires replacement. If resistance reads near zero ohms, the element is shorted. Also check for continuity between each heater terminal and ground—there should be no continuity (infinite resistance), indicating proper insulation.

Step 5: Clear Codes and Perform Operational Test After repairs, clear the fault code using diagnostic software and perform a cold start test if ambient temperature permits, or simulate conditions by allowing the engine to cool completely. Monitor the heater circuit voltage during activation (should see battery voltage applied to heater for 30-60 seconds during cranking or pre-glow cycle). If the code does not return and cold-start performance improves, the repair is successful.

Disclaimer: This guide provides general troubleshooting information for experienced technicians. Always consult the official Doosan service manual for your specific serial number and software version. If you're uncomfortable with electrical diagnostics or working on used heavy equipment, consult a certified Doosan technician or qualified diesel mechanic to prevent further damage or safety hazards.