U2105: On Chevrolet and other GM vehicles with the GMLAN network, U2105 is a network code meaning another module lost communication with the engine control module

GM lost communication with engine control module

Severity: Inspect soon

Owners report power steering loss, loss of engine power and stalling with this code, so steering and drive power can be affected and the car needs a prompt inspection.

It gets more serious if:

Stop: Stop if power steering is lost, the engine loses power or stalls, or the car goes into limp mode: pull over safely and arrange a tow.

Safety-critical system: explanation only, no DIY steps. Source: how we rate severity

U2105 in short

On Chevrolet and other GM vehicles, U2105 means another module lost contact with the engine control module. Owners and GM bulletin summaries tie it to power steering loss, no-crank and limp mode. Because steering and drive power can be affected, have a dealer diagnose it soon; do not just clear it.

GM modules talk over a network. When the body, steering or transmission modules stop hearing the engine control module, they store U2105. The code names the missing module, not the failed part.

A GM bulletin summary for the 2005-2008 Cobalt and HHR lists U2105 and U2107 among the codes for a power steering that stops working, and an Equinox summary lists U2105 with a no-crank and loss of communication with several modules. Owners of an Equinox report limp mode with U2105 and a body control module replaced three times.

This page speaks only for Chevrolet; other makes may use U2105 differently.

Pick your make

U2105 is a manufacturer-specific code: its meaning depends on who built the car.

Other makes: meaning not verified. Check with a scan tool that reads manufacturer definitions.

U2105 on Chevrolet

Most likely causes

Cause 1: Shared power, ground or network fault dropping several modules
Supported by vehicle data
Why it ranks here
The Equinox bulletin summary describes loss of communication with five modules including U2105, and a Cobalt owner reports U2105 with U2100 and U2107.
What would change this
Rises when many modules lose communication together. Falls if only the engine module is silent.
Cause 2: Body control module fault
Supported by vehicle data
Why it ranks here
An Equinox owner reports U2105 stored with other codes and the body control module being replaced three times before the fault cleared.
What would change this
Rises on Equinoxes with theft-system symptoms. Falls if the body control module tests good.
How to test the body control module (bcm)
Cause 3: Engine control module or its power fault
Possible — needs testing
Why it ranks here
TaT describes the code as no valid CAN messages from the engine control module, which can come from the module, its power or the network.
What would change this
Rises if the engine runs poorly or does not start. Falls if the module responds on a scan tool.
How to test the engine control module (ecm / pcm)

What to test first

Start at step 1. Each result tells you what it means and where to go next.

Step 1: Read all stored codes and note whether U2100, U2107, U2108 or U0100 are stored with U2105.
Low riskTool: scan tool that reads all modules
- IfSeveral network codes are stored together
  It meansLook for a shared network, power or ground fault.
  Go to step 2
- IfPower steering or no-crank symptoms come with the code
  It meansFollow the GM bulletin route with a dealer.
  Go to step 2
Step 2: Have a dealer check the engine control module power and ground, network wiring and connectors, and look for the bulletin that matches the exact car.
Best left to a shop
Warning:Loss of power steering or drive power affects vehicle control; leave testing and repair to a trained technician.
- IfA shared network or power fault is found
  It meansRepair the circuit and recheck.
  Points to: Shared power, ground or network fault dropping several modules
- IfThe body control module tests bad
  It meansReplace under the dealer procedure.
  Points to: Body control module fault

Symptoms

Power steering warning or hard steering Gets more serious: stop and have it checked.
Loss of engine power or limp mode Gets more serious: stop and have it checked.
Traction control or stability warning lights
Intermittent no-crank

Compare with: Check engine light with loss of power

How to fix

This is a safety-critical system, so we explain the code but don't give repair steps. Have it inspected by a qualified technician.

Parts and cost context

Power steering control module:GM bulletin summaries involve power steering codes; replacement should follow dealer diagnosis; labor varies; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Chevrolet

2005–2008 · Cobalt
Supported by vehicle data
Bulletin summary for power steering loss lists U2105 and U2107; owners report the same codes.
2005–2006 · Equinox
Supported by vehicle data
Bulletin summary lists U2105 with no-crank; an owner reports limp mode with U2105.
2005 · Corvette
Supported by vehicle data
U2105 with U2100, U2107 and U2108 and stability warnings.

07-02-32-007Status unverified
Diagnostic tips for power steering inoperative, DTCs including U2105 and U2107
2005–2008cobalt, hhr · issued August 1, 2009 · NHTSA 10022958
Gives diagnostic tips for a power steering that stops working with those codes. Only the NHTSA summary was read.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
02114Status unverified
No crank with loss of communication to several modules, DTCs including U2105
2005equinox · issued January 1, 2004 · NHTSA 10007456
Covers a no-crank with loss of communication to several modules. Only the NHTSA summary was read.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

All Module network (CAN bus) communication codes

U2105 questions

Does U2105 mean the engine computer failed?

Not necessarily. It means another module lost contact with it, which can come from the module, its power or ground, or the network. A dealer should test before replacing parts.

Sources and review

NHTSA complaint ODI 10176882: 2006 Chevrolet Equinox — NHTSA (owner complaint)
NHTSA complaint ODI 10251915: 2005 Chevrolet Cobalt — NHTSA (owner complaint)
GM 07-02-32-007 (NHTSA 10022958): diagnostic tips for power steering inoperative, DTCs including U2105 and U2107 — NHTSA (manufacturer communication)
GM 02114 (NHTSA 10007456): no crank with loss of communication to several modules, DTCs including U2105 — NHTSA (manufacturer communication)
U2105 No Communication With Engine Control Module (TaT Scandata) — TaT Scandata fault code library
NHTSA complaint ODI 10382088: 2005 Chevrolet Corvette — NHTSA (owner complaint)

Last reviewed: October 15, 2026
Written by: Saurabh K.
Editorial review: Pending
Technician review: Technician review pending

This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error

Severity: Inspect soon

Pick your make

Most likely causes

Cause 1: Shared power, ground or network fault dropping several modules

Cause 2: Body control module fault

Cause 3: Engine control module or its power fault

What to test first

Step 1: Read all stored codes and note whether U2100, U2107, U2108 or U0100 are stored with U2105.

Step 2: Have a dealer check the engine control module power and ground, network wiring and connectors, and look for the bulletin that matches the exact car.