P2CA4 Particulate Filter Pressure Sensor Signals Swapped A/B
P2CA4 means the engine module believes the readings of particulate filter pressure sensors A and B arrive on each other's inputs, typically because connectors, sensors or sensing hoses were interchanged during service. Such a mix-up yields values that look electrically sound but invert the pressure picture across the filter. No manufacturer documents P2CA4 publicly. Comparable checks exist: Ford's 2015 diesel summary cross-checks its absolute and delta filter pressure sensors under P246D and sets it above 1.5 kPa disagreement, and Ford's 2020–23 petrol summary flags reversed EGR delta-pressure hoses (P139A) once its signal sits under −0.5 kPa for half a minute. CARB requires plausibility checks on PM filter sensors. Wrong soot loading and mistimed regeneration follow.
Likely causes
Symptoms
- MIL on, usually right after work on the exhaust or sensors
- Regeneration too frequent or not taking place
- Implausible filter pressure values in live data
Repair estimate
Typical range across vehicles; the real cost depends on what the testing finds.
Parts involved
Related codes
References: law.cornell.edu, fordservicecontent.com, fordservicecontent.com, patents.google.com.