P243E is set when the second filter strand has finished regenerating but the soot was not burned off as planned. CARB requires a malfunction to be flagged whenever the filter does not regenerate properly under the manufacturer's intended conditions. Public manufacturer material covers only bank 1 here: for P24A2, Ford's 2023 diesels evaluate each regeneration, allow up to 40 minutes and store a fault if the soot estimate at the end is still above a threshold. Regenerations cut short by brief trips or switching off are the usual reason, followed by too little heat on that bank, a faulty temperature or pressure sensor or a fuel dosing problem. Ignored, the filter keeps loading until P243F or a power limit follows.
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
- MIL on, filter warning
- Regeneration restarts soon after the last one
- Rising soot load in live data
Most likely causes
- Regenerations interrupted by short trips or engine shut-off
- Too little heat on bank 2 (catalyst, post-injection or dosing fault)
- Faulty temperature or differential pressure signal
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
- It affects emissions.
What each character of P243E means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- 4: Emissions
- 3E: Specific fault in that system
Frequently asked questions
Can I keep driving with code P243E?
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 P243E?
The most common causes are: regenerations interrupted by short trips or engine shut-off; too little heat on bank 2 (catalyst, post-injection or dosing fault); faulty temperature or differential pressure signal.
Related codes
- P24A2Particulate Filter Regeneration Incomplete (Bank 1)
- P243DParticulate Filter Regeneration Duration (Bank 2)
- P243CParticulate Filter Regeneration Frequency (Bank 2)
- P243FParticulate Filter Restriction - Soot Accumulation Too High (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.