U0654Lost Communication With Diesel Intake Air Flow A Position Sensor
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- Diesel intake air flow valve A is the throttle ahead of the intake manifold: it creates the vacuum for high EGR rates, trims airflow for filter regeneration and shuts at switch-off. GM's 2025 diesel tables 25OBDG04A and 25OBDG04B read its angle by SENT and set U0654 when the data stop refreshing for more than 6.25 ms while the line is stuck low or high, a frame is faulty, or the counters freeze. 04A needs 200 of 250 checks, 04B 480 of 600, both every 6.25 ms after cranking with over 11 V at the relay. Type A means MIL in the first trip. GM evaluates the out-of-range codes P02E8 and P02E9 only while no such link fault exists. Ford's 2023 diesels monitor the same throttle with P02E8/P02E9 and do not list U0654. Sensor B has U0655.
- What you may notice
- MIL in the first trip
- EGR control restricted, particulate filter regeneration delayed
- Engine may shake more at switch-off
- Likely causes
- LikelyOil, soot or corrosion in the throttle body connector
- PossibleSENT signal, supply or ground wire damaged
- PossiblePosition sensor in the throttle unit failed (usually replaced with the 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.