P2178: owner reports and bulletins

Powertrain (generic, all makes). We haven't written the explanation for this code yet. Below is what owners and manufacturers have filed with NHTSA.

Got P2178 on your scanner? Tell the mechanic your year, make, model and any symptoms and you'll get the likely cause and what to check first. Ask about this code.

What owners report to NHTSA

3 complaints filed with NHTSA mention P2178, 3 of them since 2015, across 3 different models. The component owners most often filed it under: engine.

Manufacturer service bulletins that name P2178

17 technical service bulletins and manufacturer communications filed with NHTSA mention P2178, from 2 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:

  • JAGUAR E-PACE (2018, 2019, 2017), bulletin 10151650: The customer reports reduced performance with P0191-85 observed in the PCM. This may or may not also illuminate the MIL. DTCs P168F-00, P2178-00, or P144C-00 may be stored also.
  • JAGUAR F-PACE (2017, 2018, 2014, 2015), bulletin 10127288: A Customer may report one or more of: ?Lack of power ?Restricted performance displayed on Instrument Cluster (IC) ?Malfunction Indicator Light (MIL) appears on Instrument Cluster (IC). One or more of the following DTC?s …
  • LAND ROVER DISCOVERY (2016, 2017, 2018, 2015), bulletin 10145928: Issue: The customer reports reduced performance with P0191-85 observed in the PCM. This may or may not also illuminate the MIL. DTCs P168F-00, P2178-00, or P144C-00 may be stored also.
  • JAGUAR XE (2017, 2018, 2016), bulletin 10146017: Issue: The customer reports reduced performance with P0191-85 observed in the PCM. This may or may not also illuminate the MIL. DTCs P168F-00, P2178-00, or P144C-00 may be stored also.
  • JAGUAR XF (2014, 2015), bulletin 10096651: "SITUATION: THE ENGINE MALFUNCTION INDICATOR LAMP (MIL) MAY BE ILLUMINATED. UPON DIAGNOSIS, THE TECHNICIAN MAY FIND A LEAK IN THE ENGINE AIR INTAKE SYSTEM AND/OR ONE OR MORE OF THE FOLLOWING DIAGNOSTIC TROUBLE CODE (DTC)…

Sources: NHTSA Office of Defects Investigation complaint database and manufacturer communications file, snapshots September 2026. A complaint or bulletin that mentions a code is a report about that vehicle, not a statement that the code has one cause.