Network, generic

U0093 Vehicle Communication Bus H Performance

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U0093 says Vehicle Communication Bus H works, but with too many errors or too much delay. U0093 appears in no public manufacturer document. Unlike the wire codes U0094 to U009A, nothing is open or shorted; the signals are merely unreliable. A frequent background is a ground offset between modules. Texas Instruments describes the potential difference between the grounds of sender and receiver as common-mode voltage, with ISO 11898 requiring tolerance from -2 to +7 V, and lists erratic resets, lock-ups and corrupted data as results when it is exceeded. In a car this happens with loose or corroded ground points. On a CAN, each corrupted frame triggers an error frame and a repeat, which costs bandwidth long before any node is shut off.

Likely causes

Loose or corroded ground point of a Bus H module
Loose terminal causing short interruptions
Interference coupled in from nearby loads or retrofitted devices

Symptoms

  • Functions on Bus H drop out briefly and recover
  • Modules restart or freeze sporadically

Repair estimate

DifficultyHardWorkshop job
Parts and labour€50–800
Time0.5–5 h

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

Parts involved

bus h wiringmodule connector

Related codes

U008AU0092U007AU009C

References: ti.com, en.wikipedia.org, law.cornell.edu.