Code Definition

B1A28 (00) — ECM Mismatch with SKIM

System: Body  |  Type: Manufacturer-Specific  |  Make: Jeep

About B1A28

B1A28 is a manufacturer-specific body diagnostic trouble code recorded for Jeep vehicles. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

Scanning & clearing: Body (B) codes are often stored in the body control module, airbag module, or climate module. A basic OBD-II tool usually will not read body codes — an enhanced or OEM-level scan tool is typically required.

B1A28 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

On Jeep vehicles equipped with the Sentry Key Immobiliser System, the SKIM (later replaced by the Wireless Ignition Node WIN or the Wireless Control Module WCM, depending on model year) stores a secret immobiliser code that must match the corresponding code stored in the Powertrain Control Module (PCM, also referred to as the ECM). At each ignition ON event the SKIM and the PCM exchange a security challenge over the vehicle CAN network and compare the stored secret keys. DTC B1A28 subcode 00 is set when the SKIM completes this exchange but the secret key returned by the PCM does not match the ...

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