Last Updated on July 14, 2025
The P246F code is a generic powertrain diagnostic trouble code (DTC) that signifies an issue with the Exhaust Gas Temperature Sensor Circuit Performance Range Mismatch (Bank 1 Sensor 4). This sensor plays a vital role in monitoring and regulating the exhaust system’s temperature to ensure optimal performance, emissions control, and proper operation of the Diesel Particulate Filter (DPF).
When your vehicle’s Powertrain Control Module (PCM) detects a mismatch in the expected range of readings from the EGT sensor, it stores the P246F code and triggers the Check Engine Light. This mismatch often indicates that the sensor is unable to accurately report temperature data, which can affect fuel efficiency, emissions, and engine performance.
Updated Insight (2025):
In newer diesel vehicles, especially post-2023 models, manufacturers have implemented more sensitive EGT sensors and refined DPF regeneration strategies. However, the P246F code still commonly appears in vehicles where sensors begin degrading due to age, soot accumulation, or electrical issues—especially after 60,000–90,000 miles.
Related Article: P242B Trouble Code: How to Decode and Fix the Issue?
Quick Causes of the P246F Code:
- Faulty or degraded Exhaust Gas Temperature (EGT) sensor.
- Clogged or damaged Diesel Particulate Filter (DPF).
- Broken, frayed, or corroded wiring within the EGT sensor circuit.
- PCM or ECM software glitches or internal malfunction.
Common Symptoms You May Notice:
- Check Engine Light illuminated.
- Poor engine performance or rough idling.
- Limp mode activation (reduced engine power).
- Unusual exhaust odors or excessive smoke (black, white, or blue).
- Increased fuel consumption.
Why This Code Shouldn’t Be Ignored:
Ignoring the P246F code can lead to more serious problems down the line. Prolonged driving with this code active can cause permanent damage to the EGT sensor, DPF system, or even the PCM itself. Additionally, failure to maintain proper EGT readings may hinder DPF regeneration, leading to costly repairs or total DPF replacement.
Where Is the Exhaust Gas Temperature Sensor Located and How Does It Work?
To understand the P246F code, it’s essential to know where the affected sensor is located and how it functions. The Exhaust Gas Temperature Sensor (EGTS), particularly Bank 1 Sensor 4, is responsible for measuring the temperature of the exhaust gases before and after critical exhaust components like the Diesel Particulate Filter (DPF) and Diesel Oxidation Catalyst (DOC).
Exact Location of the Sensor:
In most diesel vehicles, Bank 1 Sensor 4 is typically located:
- After the Diesel Particulate Filter (DPF).
- Sometimes near or just downstream of the Selective Catalytic Reduction (SCR) system (if equipped).
- In some setups, it may be mounted near the tailpipe section of the exhaust system.
The exact position may vary slightly depending on the make and model, but it is usually the last EGT sensor in the exhaust flow sequence on Bank 1, which refers to the side of the engine with cylinder 1.
How the EGT Sensor Works:
The Exhaust Gas Temperature Sensor is a temperature-sensitive resistor (thermistor) designed to detect extreme temperatures in the exhaust stream, often exceeding 600°C (1112°F) in modern diesel vehicles during regeneration cycles.
Here’s how it works:
- The sensor sends temperature signals to the Powertrain Control Module (PCM).
- The PCM uses this data to manage DPF regeneration timing, fuel injection strategy, and turbocharger performance.
- If the readings fall outside the expected range (too low, too high, or inconsistent), the PCM triggers the P246F code, indicating a performance mismatch.
What Triggers the P246F Code?
This code is set when:
- The EGT sensor voltage or resistance is out of range.
- There’s a slow or unresponsive change in sensor output during expected temperature shifts.
- There is a significant delay in expected sensor feedback during DPF regeneration cycles.
- The sensor fails to meet programmed criteria within a specific time frame, such as during cold starts or high-load conditions.
What Are the Symptoms of DTC P246F?
When the P246F code is active, your vehicle will likely exhibit several warning signs indicating something is wrong with the exhaust gas temperature sensor circuit or the Diesel Particulate Filter (DPF) system. While some symptoms may seem minor at first, ignoring them can lead to more significant and expensive damage over time.
Most Common Symptoms of the P246F Code:
1. Check Engine Light (CEL) Illuminated
This is typically the first and most noticeable sign. When the PCM detects abnormal sensor performance, it stores the P246F code and illuminates the Check Engine Light.
2. Limp Mode Activation
To protect the engine and emissions system, the vehicle may enter limp mode—a fail-safe that reduces power and limits RPM. This makes driving sluggish and prevents further damage.
3. Poor Acceleration & Reduced Fuel Economy
When the exhaust gas readings are inaccurate, the PCM may adjust fuel injection timing and air/fuel ratios incorrectly, leading to reduced efficiency and higher fuel consumption.
4. Unusual Smoke from the Exhaust
You may notice black, white, or bluish smoke, which signals incomplete combustion or unregulated DPF regeneration cycles.
5. Hard Starting or Engine Stalling
Inconsistent EGT data can affect combustion efficiency. In cold starts or under load, you might struggle to start the vehicle, or the engine may stall shortly after ignition.
6. Excessive Rattling or Vibrations
A rough-running engine, accompanied by vibrations or rattling sounds from the exhaust system, may indicate DPF or EGR malfunctions caused by sensor inaccuracies.
Real-World Example:
Let’s say you start your diesel truck on a cold morning. The Check Engine Light comes on, and soon after, the truck struggles to maintain idle. You notice white smoke from the tailpipe and feel the power drop drastically—this is likely due to a faulty EGT sensor triggering the P246F code, preventing proper DPF regeneration and fuel regulation.
What Causes the P246F Code and How to Diagnose & Fix It
Now that we’ve covered what the P246F code means and the symptoms it causes, let’s look at the root causes and a step-by-step diagnosis and repair process. Addressing the problem early can save you from expensive DPF or engine repairs.
✅ Common Causes of the P246F Code
- Faulty Exhaust Gas Temperature Sensor (Bank 1 Sensor 4)
The sensor may have internal failure, corrosion, or incorrect resistance output due to age or excessive heat exposure. - Damaged or Clogged Diesel Particulate Filter (DPF)
A blocked DPF will raise exhaust temperatures, throwing off the expected sensor readings. - Wiring Harness Issues
Broken, frayed, shorted, or corroded wires in the EGT sensor circuit can cause intermittent or incorrect signals. - PCM (Powertrain Control Module) Failure or Software Bugs
Although rare, outdated or malfunctioning engine control software can misinterpret sensor data or fail to regulate regeneration properly. - Exhaust Leaks or Gasket Failure
A leak in the exhaust system or near the EGT sensor can alter temperature readings and cause false code triggering. - Contamination or Oil Sludge in Sensor Region
Accumulation of unburned fuel, oil, or soot can insulate the sensor or interfere with heat transfer.
🛠️ How to Diagnose and Repair the P246F Code
Here’s a step-by-step method to find and fix the issue triggering the P246F code:
Step 1: Scan and Document Codes
Use a professional OBD2 scanner to read all stored and pending DTCs. Check freeze frame data to understand when the P246F code was triggered.
Step 2: Perform a Visual Inspection
Check for:
- Damaged or disconnected sensor wiring.
- Corrosion on the sensor connector.
- Soot buildup around the sensor mount.
- Obvious DPF damage or leaks in the exhaust pipe.
Step 3: Test the EGT Sensor
Use a multimeter or ohmmeter to test the sensor’s resistance. Compare the readings to your vehicle’s service manual specifications. If resistance is out of range, replace the sensor.
Step 4: Inspect the DPF
Check for excessive backpressure or clogging. A clogged DPF can raise exhaust temperatures and cause sensor mismatch errors. If needed, perform a DPF cleaning or forced regeneration using a scan tool.
Step 5: Check & Repair Wiring
Trace the wiring from the EGT sensor to the PCM. Repair any short circuits, broken wires, or loose connections.
Step 6: Update or Reflash PCM Software
If all components are in working order but the code persists, reflash or update the PCM/ECM software. Some manufacturers release updates specifically to fix sensor misreadings or DPF issues.
Step 7: Reset the Code & Test Drive
After repairs, clear the P246F code using a scan tool. Perform a test drive under typical engine load to verify that the code does not return.
🔁 Related Diagnostic Trouble Codes (DTCs)
Several DTCs are closely related to P246F, especially those concerning Exhaust Gas Temperature Sensor Bank 1 Sensor 4. If you encounter any of the following, they may indicate similar or overlapping issues:
- P246E – Exhaust Gas Temperature Sensor Circuit Bank 1 Sensor 4
- P2470 – Exhaust Gas Temperature Sensor Circuit Low Bank 1 Sensor 4
- P2471 – Exhaust Gas Temperature Sensor Circuit High Bank 1 Sensor 4
- P2472 – Exhaust Gas Temperature Sensor Circuit Intermittent Bank 1 Sensor 4
👉 If you’re seeing multiple of these codes together, it often means the EGT sensor is completely non-functional or sending erratic data.
🌡️ Ideal Conditions for P246F Code Activation
For the P246F code to trigger, the following operating conditions are usually met:
- Engine Run Time: Typically between 300 and 327 seconds (5–5.5 minutes).
- Engine Speed: Between 700 and 3000 RPM.
- Exhaust Gas Temperature Sensor 4: Must operate at a temperature below 7°C (45°F) for at least 5 seconds (usually seen during cold starts).
- Fuel Injection Rate: Between 10 to 80 mm³ per cycle.
- DPF Regeneration Active: The engine may be in a regeneration state where exhaust gas temperature readings are critical.
- Coolant and Exhaust Temperature Sensors: Must be within 3°C of each other to avoid throwing off the logic of the PCM.
Failure in any of these conditions—especially abnormal resistance in the EGT sensor circuit—can directly contribute to the P246F code being set.
Frequently Asked Questions (FAQs)
Q1: Can I drive with a P246F code?
Technically, yes—but it’s not recommended. The code indicates possible DPF issues or incorrect EGT readings, which can trigger limp mode and reduce performance. Long-term driving may result in permanent DPF damage or poor fuel economy.
Q2: How much does it cost to fix a P246F code?
- EGT Sensor replacement: $100–$300 (parts & labor).
- DPF cleaning or replacement: $300–$2000 depending on severity.
- Wiring repair: $50–$200.
- PCM reprogramming: $100–$250.
Q3: Is the P246F code a serious issue?
Yes. While it may not seem urgent at first, it signals a problem in your emissions control system. Unresolved, it can lead to failed inspections, engine damage, and higher repair costs.
Q4: Can I clear the code myself?
You can use an OBD2 scanner to clear the P246F code, but if the root cause isn’t addressed, the code will return within a few drive cycles.
Q5: Can cold weather trigger a P246F code?
Yes. Cold starts and inconsistent heating of the EGT sensor can trigger this code, especially if the sensor is already aging or partially failed.
Final Thoughts
The P246F code points to an exhaust gas temperature sensor circuit mismatch, typically due to sensor failure, wiring issues, or a clogged DPF. Prompt diagnosis and repair are crucial to maintaining performance, fuel economy, and emission compliance.
Keep your diesel engine running efficiently by responding quickly to the P246F and related codes. Routine maintenance of the DPF system, regular software updates, and using quality diagnostic tools can go a long way in avoiding future trouble.