U0146

Lost Communication With Serial Data Gateway Module A

Communication network (CAN bus) Generic OBD-II High

What it means

U0146 means the network has lost communication with serial data gateway module A — the hub that routes messages between the vehicle's separate communication networks. Because the gateway bridges many modules, losing it can cut communication across large parts of the car at once, trigger multiple warning lights, and in some designs affect starting or drivability. It usually traces to a power/ground loss, wiring fault, or a failed gateway.

High

Can I keep driving? Often no — the gateway routes messages between the vehicle's networks, so losing it can cut communication between many modules at once, light up multiple warnings, and in some cases affect starting or drivability. Get it diagnosed before relying on the car.

Common symptoms

What you'll notice

Many warning lights on at once and widespread lost-communication codes across modules
Multiple systems (displays, comfort, sometimes powertrain) misbehaving together
Scan tool unable to reach some modules that sit behind the gateway
No-start or drivability faults if critical messages can't be routed

Common causes

Most likely first

Loss of power or ground to the gateway moduleLikely
Wiring or connector fault at the gateway (opens, corrosion, damage)Common
CAN bus fault on a branch the gateway bridgesCommon
Software/configuration fault or a gateway that needs reprogramming after serviceLess often
Failed serial data gateway moduleLess often

How to diagnose & fix

Work through it in order

Scan all modules — a gateway failure typically shows many modules offline at once, especially those behind the gateway.
Check power and ground at the gateway connector; the gateway must be powered for the network to route messages.
Inspect the gateway wiring and connectors for corrosion, damage, or water intrusion.
Verify the bus branches on each side of the gateway are healthy (resistance/voltage checks).
If supply and wiring are good, suspect the gateway module — replace and program per the manufacturer procedure, then re-test.

FAQ

Quick answers

Is it safe to drive with U0146?+

Be cautious. The gateway is a hub for vehicle communication, so losing it can knock many systems offline together and, depending on the design, affect starting or drivability. Have it diagnosed before depending on the vehicle.

Can I just clear U0146?+

It clears, but returns if the gateway has lost power, has a wiring fault, or has failed. Because it affects the whole network, diagnose the cause rather than clearing it.

Related codes

Often seen with U0146

U0073Control Module Communication Bus A Off U0100Lost Communication With ECM/PCM "A"U0140Lost Communication With Body Control Modul U0155Lost Communication With Instrument Panel C

Read & clear U0146 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

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✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX