P2CDAAlternative Fuel Tank A Vacuum Insulation Deteriorated
- Generic OBD-II code · Powertrain
- Matters for the ITP
- How the car detects it
- P2CDA concerns cryogenic fuel storage, in practice liquefied natural gas (LNG) and possibly liquid hydrogen, kept in a double-walled tank whose gap is evacuated. Once that vacuum softens, heat leaks in, the liquid boils faster and pressure climbs until the relief valve vents gas. Chart, a maker of LNG truck tanks, separates true vacuum loss from other causes by an eight-hour pressure rise test combined with an outer shell that feels cold or shows condensation. A Caterpillar patent lets the ECM compare pressure at key-off and key-on against a predicted rise and rate hold time, with under one day flagged as poor. No manufacturer documents this code publicly. The tank pressure sensor codes start at P019E. Expect shorter standing times before venting and lost fuel.
- What you may notice
- Tank pressure rises quickly while the vehicle stands, relief valve vents gas
- Frost or condensation on the outer tank shell
- Fuel loss and shorter standing time after refuelling
- Likely causes
- LikelyVacuum between inner and outer tank wall lost through a leaking weld, fitting or seal
- PossibleGradual vacuum decay from outgassing over years of service, tank due for pump-down
- PossibleDent or impact damage to the outer shell breaching the insulation space
- RarePressure rise from another cause (economizer, pressure regulator, sensor) misread as insulation loss
- Inspection (ITP)
- Can matter for the ITP: it concerns the emissions system.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €500 – €8,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.