Drive DTC
Sign in Get Drive DTC

Trouble code libraryNetwork and modules

U0100 Lost communication with the engine computer

Generic SAE definitionLost communication with ECM/PCM A

Short trips onlyDrive it only if you have to, gently and not far. Get it fixed right away.

Check this first

Check the battery terminals and grounds – weak power causes more of these than broken wires do.

What usually fixes it

In the order a good shop checks them. Typical total: $114–$1,906 at $130 an hour.

  1. Battery, terminals and grounds

    $114–$512

    Low or dirty power makes modules drop off the network.

  2. Network wiring

    $258–$725

    A damaged wire between modules.

  3. Engine computer

    $660–$1,906

    A module that has genuinely failed.

Code titles are the generic SAE definitions. Prices are typical US parts and labor for a common car or light truck – a guide for judging a quote, not a quote. Always confirm a repair against the vehicle in front of you.

Drive DTC

See what your vehicle says about U0100

A stored code is a headline, not the story. The vehicle also holds the conditions from the moment the code set, how close each part is to the limit it fails at, what the fuel trims are doing, and whether the fault is still happening. Drive DTC reads all of it with a USB adapter and a Windows PC – read-only by design.

  • Free to start
  • Codes in plain English
  • One-time purchases, no subscription
Get Drive DTC Check a VIN for recalls
Diagnose · Trouble codes
The Trouble codes screen in Drive DTC: stored, pending and permanent counts, then C0040-13 explained in plain English with what to check first, likely fixes in order and typical cost ranges

More in Network and modules

All 8 codes in this group
U0073Control module communication bus A off U0101Lost communication with TCM U0121Lost communication with anti-lock brake system (ABS) module U0140Lost communication with body control module U0151Lost communication with restraints control module U0155Lost communication with instrument panel cluster (IPC)