P2894Cylinder 2 Ion Current Sense Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P2894 covers a general fault in the ion current circuit of cylinder 2: the processing electronics get no evaluable signal from this plug. Which physical position cylinder 2 occupies depends on the maker's numbering. On Saab's Trionic four-cylinder, cylinders 2 and 3 are fired together by waste spark during start-up, and only the ion signals tell the engine management which of the two actually burned; a missing cylinder 2 signal can thus prolong cranking. In the 2009 Saab 9-3 module, cylinder 2 has its own ion input and trigger line and feeds the second combustion signal together with cylinder 4. No manufacturer publishes P2894; checking coil 2, its wiring and the plug comes first, and swapping coils between cylinders shows whether the fault moves.
- What you may notice
- MIL with a stored cylinder 2 ion fault
- Hard or longer starting in some cases
- Cautious ignition timing and slightly less power
- Likely causes
- LikelyIgnition coil of cylinder 2 with dead ion measurement
- PossibleInterrupted ion signal path from coil 2
- RareDefective cylinder 2 input in the processing module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €60 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.