P243C is stored when the bank 2 particulate filter needs regeneration more often than its calibration allows. CARB requires diesel OBD to recognise regeneration so frequent that emissions would rise above the limit. No manufacturer documents this bank 2 code publicly, so the bank 1 code P2459 serves as the reference: Ford's 2023 diesels flag it once completed regenerations occur, on average, less than roughly 40 km apart. Excess soot from the engine side of that bank, for example a leaking injector, an EGR or boost fault, or a pressure reading that overstates the load, makes the filter look full too early. Every extra regeneration burns fuel and can thin the engine oil. If the other bank regenerates at normal intervals, compare what differs on this side.
Medium severity. Can I keep driving?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.
Bank 2 is the side without cylinder 1, so it only exists on V or boxer engines.
Symptoms
- Regeneration running unusually often
- Higher fuel consumption, rising oil level
- MIL on
Most likely causes
- Too much soot from bank 2 cylinders (injector, EGR or boost fault)
- Pressure sensor or hose overstating the bank 2 soot load
- Filter partly filled with ash, leaving little soot capacity
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: hard
- It affects emissions.
What each character of P243C means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- 4: Emissions
- 3C: Specific fault in that system
Frequently asked questions
Can I keep driving with code P243C?
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 P243C?
The most common causes are: too much soot from bank 2 cylinders (injector, EGR or boost fault); pressure sensor or hose overstating the bank 2 soot load; filter partly filled with ash, leaving little soot capacity.
Related codes
- P2459Diesel Particulate Filter Regeneration Frequency
- P243DParticulate Filter Regeneration Duration (Bank 2)
- P243EParticulate Filter Regeneration Incomplete (Bank 2)
- P24A3Particulate Filter Restriction - Soot Accumulation (Bank 2)
Sources
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.