P243B: Particulate Filter Restriction - Forced Limited Power (Bank 2)

P243B means the second particulate filter is so restricted that the engine controller cuts power to protect engine and filter. Ford documents the code in its 2024–2025 OBD summary for gasoline engines, as part of the petrol particulate filter monitor next to P246C for bank 1. Once the filter has been above 250 °C for 30 s and exhaust flow lies between 400 and 850 m³/h, a normalised back pressure above 1.0 for 5 s sets the fault. That makes it one of the few bank 2 filter codes with public thresholds, and it shows the code is not limited to diesels. Likely causes are a filter overloaded with soot or ash, a dented pipe, or a pressure sensor or hose reading too high. Until the restriction is cleared the engine stays in reduced power. A high soot load on this bank without the power limit is P243F.

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

Symptoms

• Noticeably reduced engine power
• MIL on
• Poor acceleration at higher speed

Most likely causes

• Bank 2 filter overloaded with soot or ash
• Damaged or blocked exhaust pipe on bank 2
• Pressure sensor or hose on bank 2 reporting too high a pressure

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 differential pressure sensor's hoses
3. Check the temperatures before and after the filter
4. Fix any fuel injection or EGR codes before regenerating
5. 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 P243B means

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

Frequently asked questions

Can I keep driving with code P243B?

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 P243B?

The most common causes are: bank 2 filter overloaded with soot or ash; damaged or blocked exhaust pipe on bank 2; pressure sensor or hose on bank 2 reporting too high a pressure.

Related codes

• P246CParticulate Filter Restriction - Forced Limited Power (Bank 1)
• P243FParticulate Filter Restriction - Soot Accumulation Too High (Bank 2)
• P24A3Particulate Filter Restriction - Soot Accumulation (Bank 2)
• P226EParticulate Filter Deteriorated/Missing Substrate (Bank 2)

Sources

• fordservicecontent.com: OBDSM2400OUTPUT 16Jul2024 WSM final V2 MCS7001
• 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.