P246E – Exhaust Gas Temperature Sensor Circuit, Bank 1 Sensor 4

Meaning of Code P246E

Code P246E indicates that the Exhaust Gas Temperature Sensor (EGTS) located at Bank 1, Sensor 4 is sending a signal outside the manufacturer’s specifications. This sensor monitors the exhaust gas temperature upstream of the Diesel Oxidation Catalyst (DOC) or the Diesel Particulate Filter (DPF). The PCM (Powertrain Control Module) uses this data to:

• 🔥 Optimize DPF regeneration (burning off particulates).

• 🌍 Control pollutant emissions (NOx, CO).

• 🚗 Adjust engine parameters (injection, EGR).

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Common Symptoms

• 🚨 Check Engine light on (Check Engine).

• 📉 Loss of power (limp mode to protect the DPF).

• ⛽ Increased fuel consumption.

• 💨 Excessive smoke from the exhaust (white or black).

• ⚠️ DPF warning message (if the vehicle is equipped with one).

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Possible Causes

1. Faulty EGTS sensor:

   • Thermal drift, internal resistance out of range, or slow response.

2. Wiring issues:

   • Short circuit, open circuit, or corrosion in the sensor harness.

3. Poor electrical connection:

   • Oxidized pins, improperly engaged connector.

4. Exhaust leaks:

   • Cracks in the exhaust manifold, faulty gaskets.

5. Sensor fouling:

   • Soot or particle buildup distorting measurements.

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Step-by-Step Diagnostic Procedure

1. Visual Inspection

• Locate the EGTS sensor: Usually situated near the DOC or DPF (refer to the service manual).

• Check the harness and connector:

  • Look for pinched wires, burnt insulation, or signs of corrosion.

  • Clean the pins with contact spray (CRC Electrical Cleaner).

2. EGTS Sensor Testing

• Resistance measurement:

  • Disconnect the sensor and use a multimeter in ohmmeter mode (Ω).

  • Compare the resistance at room temperature with manufacturer specifications (e.g., 200–300 kΩ at 20°C).

  • If out of range → Replace the sensor.

• Voltage test:

  • Reconnect the sensor, turn the ignition on.

  • Measure the voltage between the signal wire and ground (expected: 0.1–4.8 V, varying with temperature).

3. Exhaust Leak Check

• Visually inspect the exhaust path (manifold, pipes, gaskets).

• Use a smoke generator or soapy water to detect leaks near the sensor.

4. Sensor Cleaning

• Remove the sensor and clean it with a high-temperature degreasing spray (*WD-40 Specialist*).

• Avoid abrasive tools to prevent damaging the sensing element.

5. PCM Verification

• Use an advanced diagnostic tool (e.g., Autel MaxiCOM, Snap-On Verus) to:

  • Read live data (displayed temperature vs. actual).

  • Check for related codes (e.g., P246A-P246D).

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Repair Solutions

1. Replace the EGTS sensor if faulty (prefer OEM parts).

2. Repair the harness:

   • Replace damaged wires and protect them with heat shielding.

3. Eliminate exhaust leaks:

   • Weld cracks or replace faulty gaskets.

4. Update the PCM if a TSB (Technical Service Bulletin) exists for this code.

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Specific Cases

• Diesel with DPF:

  • Prolonged EGTS sensor failure can block DPF regeneration, leading to clogging.

  • After repair, force a forced regeneration via the diagnostic tool.

• High-mileage vehicles:

  • Check the condition of the DOC/DPF (a damaged catalyst can overload the sensor).

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Important Tips

• 🔧 Required tools:

  • Digital multimeter.

  • Manufacturer-compatible diagnostic tool.

  • High-temperature resistant degreasing spray.

• ⚠️ Safety:

  • Work on a cold engine to avoid burns.

  • Wear gloves and safety glasses.

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Post-Repair

• Clear the P246E code and perform a road test.

• Monitor live exhaust temperatures to confirm proper operation.

Note: If the code reappears, check the PCM’s 5V reference circuit and the sensor ground. A faulty sensor can also be a symptom of a clogged DPF.