P243F: Particulate Filter Restriction - Soot Accumulation Too High (Bank 2)

P243F means the soot load estimated for the bank 2 particulate filter has climbed past the level that a normal regeneration can still handle safely. Burning off too much soot at once can overheat and crack the substrate, so many engines then block automatic regeneration and call for a service regeneration or a new filter. No manufacturer documents P243F publicly. For the bank 1 analogue P2463, GM's 2018 diesels estimate soot from the differential pressure and confirm the fault after 120 failures in 150 samples; the same GM table, oddly, labels P24A4, the J2012 bank 1 twin of P243F, as ash accumulation. Typical causes are long stretches of short trips or idling, regenerations that keep aborting and engine faults that raise soot output on that bank. Power reduction (P243B) may follow.

Bank 2 is the side without cylinder 1, so it only exists on V or boxer engines.

Symptoms

• MIL and filter warning on
• Automatic regeneration blocked, service regeneration needed
• Reduced power possible

Most likely causes

• Repeatedly aborted regenerations, short trips or long idling
• Engine fault raising soot output on bank 2 (injector, EGR, boost)
• Pressure sensor or hose overstating the soot load

What to check, in order

Start with the simplest. You can tick off each step.

1. Read the soot load and differential pressure with a scanner
2. Check the sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
3. Check the differential pressure sensor's hoses
4. Check the temperatures before and after the filter
5. Fix any fuel injection or EGR codes before regenerating
6. Perform a regeneration while driving or at a repair shop when the diagnosis allows it

Good to know

• Repair difficulty: hard
• It can trigger limp mode.
• It affects emissions.

What each character of P243F means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 4: Emissions
• 3F: Specific fault in that system

Frequently asked questions

Can I keep driving with code P243F?

If the light is on steadily, take a highway drive or go to a repair shop soon. If the car is in limp mode or the light is flashing, do not push the engine.

What causes code P243F?

The most common causes are: repeatedly aborted regenerations, short trips or long idling; engine fault raising soot output on bank 2 (injector, EGR, boost); pressure sensor or hose overstating the soot load.

Related codes

• P24A4Particulate Filter Restriction - Soot Accumulation Too High (Bank 1)
• P24A3Particulate Filter Restriction - Soot Accumulation (Bank 2)
• P243BParticulate Filter Restriction - Forced Limited Power (Bank 2)
• P243EParticulate Filter Regeneration Incomplete (Bank 2)
• P243AParticulate Filter Restriction - Ash Accumulation (Bank 2)

Sources

• gsi.ext.gm.com: 18OBDG04 Engine Diagnostics
• law.cornell.edu: 13 CCR 1968.2

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.