OBD-II code · Powertrain (generic, extended)

P2CA4 Particulate Filter Pressure Sensor Signals Swapped A/B

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.

Is it safe to drive with P2CA4?

Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.

Common causes

  • Most likelySensor connectors A and B swapped during service
  • PossibleSensors installed in wrong positions

Symptoms

  • Check engine light or DPF warning light on
  • Power loss / limp mode
  • Increased fuel consumption
  • Failed forced regeneration attempts

Repair at a glance

Difficulty
Easy
DIY friendly
Often, with basic tools
Typical labour
0.2–1 h
Emissions test
Likely to fail
After the fix
A drive cycle is needed before the light stays off
Parts involved
Pf Pressure Sensor A, Pf Pressure Sensor B, Wiring Harness

Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.