The ECM detects that the particulate filter pressure sensor signals A and B are reversed - low-pressure side reads as high-pressure side and vice versa. Most likely a wiring swap during service.
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.
Symptoms
- Check engine light or DPF warning light on
- Power loss / limp mode
- Increased fuel consumption
- Failed forced regeneration attempts
Most likely causes
- Sensor connectors A and B swapped during service
- Sensors installed in wrong positions
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: easy
- It affects emissions.
What each character of P2CA4 means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- C: Subsystem depends on the code range
- A4: Specific fault in that system
Frequently asked questions
Can I keep driving with code P2CA4?
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 P2CA4?
The most common causes are: sensor connectors A and B swapped during service; sensors installed in wrong positions.
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.