P246D — Diesel Particulate Filter Pressure Sensor “A”/”B” Correlation #

Please note: The exact wording of this DTC may vary depending on the manufacturer.

Known variations of this code label:

• P246D – Diesel Particulate Filter Pressure Sensor “A”/”B” Correlation (General)
• P246D – DPF Pressure Sensor Signal Correlation Fault (Ford)
• P246D – Diesel Particulate Filter Differential Pressure Sensor Performance (GM/Chevrolet)
• P246D – DPF Pressure Sensor Plausibility Error (Mercedes-Benz)

Code P246D summary #

P246D refers to a correlation issue detected between the signals from the Diesel Particulate Filter (DPF) Pressure Sensors “A” and “B”. The DPF is an emissions-control device that traps soot particles from diesel exhaust, and its differential pressure sensors monitor how well exhaust gasses are flowing through the filter. When the Engine Control Module (ECM) or Powertrain Control Module (PCM) detects the readings from these two sensors don’t align as expected, it sets the P246D code. This can indicate either a sensor fault, wiring issue, or a problem with the DPF itself. Left unchecked, this fault may impact emissions performance, fuel efficiency, and ultimately the health of your diesel engine.

Common symptoms for code P246D #

The presence of code P246D may not immediately bring your vehicle to a halt, but it can cause a variety of noticeable symptoms. Since the DPF is vital for keeping your diesel clean and efficient, any issue here can have a ripple effect across your driveability and emissions. You might observe:

• Illuminated Check Engine Light (CEL)
• Reduced engine power or limp mode activation
• Increased exhaust smoke
• Decreased fuel economy
• Regeneration cycles failing to complete or occurring too frequently
• Strong diesel odor from the exhaust

Likely causes for code P246D (in order of frequency) #

The most common reasons for a P246D involve sensor malfunctions or wiring faults, but mechanical issues can also play a role. Here are the most likely suspects, ordered from most to least frequent:

1. Faulty DPF Differential Pressure Sensor(s) (“A” and/or “B”)
2. Wiring issues (corroded connectors, damaged harness, poor ground)
3. Plugged or leaking DPF pressure sensor hoses
4. Diesel Particulate Filter partially blocked or failed
5. ECM/PCM software issue or failed module (rare)

Step-by-step diagnosis for code P246D #

Diagnosing P246D involves methodically checking both the sensors and the DPF system. Here’s a guided approach:

1. Read stored codes and freeze frame data with a professional scan tool.
2. Visually inspect DPF pressure sensor(s) “A” and “B” and their wiring for damage or corrosion.
3. Check the sensor hoses for blockages, cracks, or disconnections.
4. With the engine off, use a multimeter to verify sensor reference voltage, ground, and signal continuity to the ECM/PCM.
5. Compare live sensor readings at idle and under load; values should be within manufacturer specs and track together.
6. Perform a manual DPF differential pressure test (if possible) and inspect the DPF for excessive soot or restriction.
7. Verify ECM/PCM software is up to date.
8. If all checks pass, replace the suspect sensor(s) and clear codes. Retest.

Possible repairs for code P246D #

Once you’ve pinpointed the cause, the following repairs are commonly performed to clear P246D:

• Replace faulty DPF pressure sensor(s) (“A” and/or “B”)
• Repair or replace damaged wiring or connectors at the pressure sensors
• Clean or replace blocked or leaking pressure sensor hoses
• Clean or replace the Diesel Particulate Filter if restricted or failed
• Update ECM/PCM software or replace module (rare, after all other options exhausted)

Can you drive with code P246D? #

Limited — Not recommended for extended driving. While your vehicle may continue to operate with the P246D code set, you risk entering limp mode, experiencing poor performance, or causing further damage to the DPF or engine. Prolonged driving with this fault may lead to more expensive repairs due to soot buildup, failed regeneration, or increased emissions. It’s best to have the issue diagnosed and repaired as soon as possible.

Vehicles most affected by code P246D #

This code is seen across many OEM (Original Equipment Manufacturer) diesel applications, but is especially common in vehicles using advanced DPF systems with dual or redundant sensors. The following makes are most often reported:

• Ford (F-Series Super Duty, Transit, Ranger Diesel)
• Chevrolet/GMC (Silverado HD, Colorado/Canyon Diesel, Express/Savana Diesel)
• Ram (2500/3500 Diesel, ProMaster Diesel)
• Mercedes-Benz (Sprinter, Bluetec Diesel models)
• Volkswagen (Passat, Touareg, Amarok Diesel)
• Land Rover/Jaguar (Range Rover, Discovery, Jaguar XE/XF Diesel)

Common mistakes & best practices for P246D #

When addressing P246D, even seasoned techs can miss the mark. Avoid these pitfalls and follow best practices:

• Replacing sensors without inspecting the hoses: Blocked or leaking sensor hoses are a frequent, overlooked cause.
• Ignoring wiring checks: Corroded or damaged wiring/connectors can mimic sensor faults.
• Not checking both sensors: Since correlation is the issue, always test “A” and “B” together.
• Skipping live data comparison: Static sensor tests miss dynamic faults; always compare readings under load.
• Neglecting DPF health: A partially blocked DPF can trigger false sensor faults.

Quick FAQ for code P246D #

Q: Can a simple loose connector cause P246D?
A: Absolutely. Corroded or loose sensor connectors are a common source of correlation faults and should be your first check.

Q: Does clearing the code resolve the problem?
A: Clearing the code without fixing the underlying issue is only a temporary solution. The code will return if the root cause isn’t addressed.

Q: Is sensor calibration required after replacement?
A: On some OEM applications, yes — especially when both sensors are replaced. Always follow manufacturer procedures for sensor adaptation or calibration.