Network, generic

U0032 Vehicle Communication Bus A (+) High

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U0032 reports excess voltage on the (+) line of Vehicle Communication Bus A, usually from contact with battery voltage. If Bus A is a two-wire CAN of the high-speed type, as Audi's sensor/hybrid CAN, the (+) wire is CAN-High. onsemi's bench tests show frames still getting through with CAN-High at 12 V, only with distorted levels; NXP counts such shorts among hidden bus failures that a plain transceiver does not report. Faults therefore show up as sporadic message errors or a single module complaining while the vehicle behaves normally, quite unlike the hard stop of U0031. No manufacturer documents U0032 publicly. A reading close to battery voltage on CAN-High against ground, instead of somewhere between 2.5 V and 3.5 V, confirms it; a harness rubbed through next to a supply cable or a wet connector is the usual cause.

Likely causes

(+) wire chafed against a battery or ignition feed
Water in a connector bridging the (+) wire to a supply pin
Aftermarket device connected to the bus wire

Symptoms

  • Sporadic warnings or brief function dropouts
  • Only one module reports the fault, vehicle otherwise normal

Repair estimate

DifficultyHardWorkshop job
Parts and labour€60–700
Time1–5 h

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

Parts involved

bus a wiringbus a transceiver

Related codes

U0005U0028U0030U0031U0035

References: onsemi.com, nxp.com, law.cornell.edu, static.nhtsa.gov.