U0017

Medium Speed CAN Communication Bus (-) High

Communication network (CAN bus) Generic OBD-II Medium

What it means

U0017 means the negative wire of the medium-speed CAN bus is reading higher than expected, so modules on that network can't talk reliably. The medium-speed bus usually carries body, cluster, and comfort data, so you'll typically see warning lights and features misbehaving rather than an engine that won't run. It points to a wiring, connector, or module fault on that bus.

Medium

Can I keep driving? Usually yes — the engine still runs, but expect warning lights and some body/comfort features to act up until the bus wiring is fixed.

Common symptoms

What you'll notice

Check-engine or other warning lights on the dash
One or more modules stop responding (cluster, HVAC, body features)
Intermittent electrical glitches or features dropping in and out
Other communication (U-series) codes stored alongside this one

Common causes

Most likely first

Short to voltage or chafed insulation on the medium-speed CAN (-) wireLikely
Corroded, loose, or backed-out connector pins on the busCommon
Water intrusion into a connector or moduleCommon
A failing module dragging the bus line highLess often
Damaged wiring from a prior repair or rodent damageLess often

How to diagnose & fix

Work through it in order

Scan all modules and record every U-code — the pattern points to the affected bus branch.
Inspect CAN wiring and connectors along the medium-speed bus for chafing, corrosion, or water.
Back-probe the bus (-) line and check for a short to voltage against a wiring diagram.
Disconnect suspect modules one at a time to find one pulling the line high.
Repair the wiring or connector, clear the code, and confirm all modules report.

FAQ

Quick answers

Is it safe to drive with U0017?+

Usually the engine runs fine, but a bus fault can disable safety-related warnings and body features. Have it checked soon rather than ignoring it.

Can I just clear U0017?+

It clears, but it returns as soon as the bus fault reappears. The wiring or connector problem has to be repaired.

Related codes

Often seen with U0017

U0010Medium Speed CAN Communication Bus U0011Medium Speed CAN Communication Bus Perform U0023Low Speed CAN Communication Bus (+) High U0027Low Speed CAN Communication Bus (-) shorte

Read & clear U0017 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