Network, generic

U0068 Vehicle Communication Bus E (+) High

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U0068 flags the (+) wire of Vehicle Communication Bus E at an excessive voltage, from battery or a 5 V rail. If Bus E is a high-speed CAN, the line in question is CAN-High, and traffic continues: onsemi saw frames pass with altered dominant levels, NXP files the case under hidden failures. Detecting it therefore depends on the module. NXP's TJA1041 note explains that a diagnosing transceiver must itself send at least four sufficiently long dominant phases before its failure flag is valid, and recommends reading the flag once a frame has finished, because arbitration with other senders can distort the measurement. That is why only some modules on Bus E, or none, may store the code. No manufacturer documents U0068 publicly. A meter on CAN-High showing roughly supply voltage to ground proves it.

Likely causes

(+) wire of Bus E chafed against a battery or 5 V feed
Moisture in a connector bridging the bus wire to supply
Aftermarket device connected to the bus wire

Symptoms

  • Usually no symptom, code found by chance
  • Code stored in only one module on Bus E

Repair estimate

DifficultyHardWorkshop job
Parts and labour€60–700
Time0.5–5 h

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

Parts involved

bus e wiringcan transceiver

Related codes

U0041U0059U0064U0066U0067

References: nxp.com, onsemi.com, nxp.com.