Network, generic

U0680 Lost Communication With Barometric Pressure Sensor B

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modeNo

The letter B need not mean a second ambient sensor; it can be any further pressure input that sees near-atmospheric air. GM's 23OBDG07 and 24OBDG07 tables, written for a program with two throttle bodies, use barometric sensor B for the pressure ahead of the bank 2 throttle and send it over SENT. U0680 is stored when the frames carrying the high and low line pressure of bank 2 come in with a wrong data length code for 1.5 s; the MIL follows after two trips. The checks of the value itself are P222C and P222D (raw reading under 50 or over 115 kPa) and P222B (plausibility against ambient pressure). U068A covers the bank 1 counterpart. Air mass on bank 2 then has to be estimated without its reference.

Likely causes

SENT signal, supply or ground wire to the bank 2 pressure sensor faulty

Connector at the sensor ahead of the throttle loose or wet

Pressure sensor sends malformed frames

Engine controller software or SENT input fault

Symptoms

Check engine light after two trips
Uneven running between banks possible
Additional pressure plausibility codes

Repair estimate

DifficultyMediumDIY possible

Parts and labour€50–400

Time0.3–2 h

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

Parts involved

baro sensor bvehicle bus wiring

References: gsi.ext.gm.com, gsi.ext.gm.com, law.cornell.edu.