U0688Lost Communication With Throttle Position Sensor/Switch G
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- Throttle sensor G is the second track of a second throttle body. GM's 23OBDG07 and 24OBDG07 tables, for a program with one throttle per bank, use it for throttle position sensor 2 on bank 2. Both tracks of that throttle travel in one SENT stream, so GM sets U0688 together with U0608 (sensor 1, bank 2) when the line carries no signal, pulse widths fall outside their window or the calibration pulse is off, within 0.13 s and MIL in one trip. NXP's KMA215 shows why: its dual throttle format packs the angle and its inverted copy into a single frame. Raw value checks of track G are P212C under 0.195 V and P212D over 4.805 V, P212B checks synchronisation. Bank 2's throttle can then no longer be positioned reliably, so power is reduced.
- What you may notice
- Check engine light on the first trip
- Reduced power, uneven running between banks
- U0608 stored at the same time
- Likely causes
- LikelySENT, supply or ground wire to the bank 2 throttle body faulty
- PossibleThrottle body connector loose, wet or corroded
- PossibleSensor electronics in the throttle body failed (replaced as a unit)
- RareEngine controller SENT input fault
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €60 – €700
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.