P1921

No Bus data From TRIONIC.

P1921:

Fault symptoms
No bus communication with the Trionic.

Diagnostic help
Some of the following symptoms may be observable:
- Diagnostic trouble code (P1908 in Trionic, if Trionic can be contacted)
- Misfiring
- Engine will not start

Check wiring harness.
Jiggle the wiring harness at several points and in different directions to detect intermittent breaks and short-circuits in the leads.
Observe the multimeter, test lamp or diagnostic tool during the test.