Powertrain, generic (extended)

P28C0 Ion Sense Module Supply Voltage Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P28C0 points to a fault in the power feed of the module that conditions ion signals – typically an open fuse, relay contact or wire, so the module is not powered at all. On Saab's Trionic T8 that module receives battery voltage via the main relay and its ground from a body point, and on the older T7 the ignition cassette took the same route. Saab's nearest code, P1310 (bank 2: P1320), required a turning crankshaft and more than 6 V at the main relay, then flagged the fault when every trigger output stayed under 2 V for one second. Saab cut fuel in response, on the V6 for every cylinder although just one cassette had failed, yet treated it as Type III without a warning lamp. No manufacturer documents P28C0 itself. P28C1 and P28C2 cover a supply that is present but too low or too high.

Likely causes

Blown fuse in the ion sense module feed
Main relay not switching through or burnt contact
Open supply wire or loose ground point of the module
Internal fault in the module's power stage

Symptoms

  • Engine cranks but does not start, or cuts out while driving
  • Ion-based misfire and knock detection lost on all cylinders
  • Warning lamp behaviour depends on the manufacturer

Repair estimate

DifficultyMediumDIY possible
Parts and labour€10–600
Time0.3–2.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

ion sense modulewiring harness

Related codes

P28C1P28C2P0685P0560

References: law.cornell.edu, saabwisonline.com, saabwisonline.com, saabwisonline.com.