U0654 code meaning
Lost Communication With Diesel Intake Air Flow A Position Sensor
Network system Generic code U06xx codes Check engine light
What U0654 means
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.
U0654 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0654
- MIL in the first trip
- EGR control restricted, particulate filter regeneration delayed
- Engine may shake more at switch-off
Common causes of U0654
- Most 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)
- Less likelyEngine controller SENT input fault
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Diesel intake airflow position sensor aVehicle bus wiring
What each part of U0654 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 54 | The exact fault in that area. |
What to do next
- Note U0654 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U0654
What does U0654 mean?
U0654 means "Lost Communication With Diesel Intake Air Flow A Position Sensor". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with U0654?
Drive gently and only to a workshop. With U0654 the car can go into limp mode (reduced power) to protect itself.
Will U0654 fail an emissions test?
Yes, it can. U0654 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is U0654 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will U0654 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.