How is fault code U0073 fixed?

A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training. 1. Test and load-test the battery and check the charging voltage first. A flat or tired battery is the cheapest cause and you want it ruled out before you chase wiring for hours 2. Scan the whole car, not just the engine ECU, and note every U-code that comes up alongside U0073. The pattern of which modules report it tells you roughly where on the bus the break is 3. Check and clean every main earth point and the battery terminals. A poor earth mimics a wiring fault and costs nothing to put right 4. Go over the CAN wiring by hand, looking for chafing, green corrosion or water ingress, and pay attention to harness sections that flex or sit low where damp collects 5. Back-probe the CAN-high and CAN-low lines with a multimeter. A healthy bus reads around 60 ohms across the two lines at rest, roughly 120 ohms on each terminating resistor; readings well off that point to a wiring break or a duff module 6. If the wiring checks out, disconnect modules one at a time on the network to find the one t

A faulty control module, A problem with the CAN bus

Jump to the fix

Severity

Medium

Can I keep driving?

Usually drivable, but get it diagnosed without delay.

First step

A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training. 1. Test and load-test the battery and check the charging voltage first. A flat or tired battery is the cheapest cause and you want it ruled out before you chase wiring for hours 2. Scan the whole car, not just the engine ECU, and note every U-code that comes up alongside U0073.

UNetwork
0Generic code
0Network / Communication
73Sequence number

What does it mean?

Vehicles are controlled by electronic means in some fashion or another. Whether actively controlled with a button or switch or passively controlled by a module, electrical systems are operated based on the input supplied to them and their output response. In turn, modules communicate those parameters with each other so all systems operate seamlessly. Communication is done via a data bus network, often referred to as a Controller Area Network (CANbus).

The communication is crucial to ensure body, engine, transmission, anti-lock brakes, and all other systems are able to safely work together. When communication breaks down intermittently or fully between modules, a code is set in a module to indicate the failure. The code, U0073, can register in one or more modules: powertrain control module (PCM), transmission control module (TCM), anti-lock brake (ABS) module, or body control module (BCM) in various locations.

Typically, the code sets in the module that experienced a loss of communication.

Symptoms

Likely causes

How to fix it

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This information follows the generic OBD-II definition and does not replace a vehicle-specific diagnosis. The severity rating is rule-based; an authorised diagnostic reading is required for a definitive answer.