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Home/DTC Codes/Fiat/Cronos/2018-2025 1.3L I4 Flex Firefly/U0009
U0009

High Speed CAN Communication Bus Shorted Together

2018-2025 Fiat Cronos 1.3L I4 Flex Firefly

Critical SeverityNetworkGeneric (SAE)

Description

CAN H and CAN L wires are shorted to each other, preventing differential signaling on the bus.

Symptoms

  • Complete CAN bus failure
  • No communication with any module on bus
  • Vehicle may not start

Common Causes

  • CAN H and CAN L wires shorted together
  • Connector pin damage
  • Crushed wiring harness
  • Rodent damage to wiring

Diagnostic Steps

  1. Measure resistance between CAN H and CAN L (should be ~60 ohms with termination)
  2. Inspect wiring for physical damage
  3. Check connectors for bent pins
  4. Disconnect modules and measure resistance at each segment

Repair Notes

Locate the short between CAN H and CAN L. Common in door jambs and under-dash wiring.

Related Codes

U0001High Speed CAN Communication BusU0003High Speed CAN Communication Bus (+) OpenU0006High Speed CAN Communication Bus (-) Open

Other Network Codes

U0009 on Other Vehicles

Fiat 124 Spider

2017-2020 1.4L I4 Turbo

Fiat 126p Maluch

1973-2000 0.65L I2 Air-Cooled

Fiat 126p Maluch

1987-2000 0.7L I2 Air-Cooled

Fiat 500

2012-2019 1.4L I4

Fiat 500 Abarth

2012-2019 1.4L I4 Turbo

Fiat 500 BR

2011-2020 1.4L I4 Flex Fire Evo

Fiat 500 PL

2007-2025 1.0L I3 Hybrid FireFly 70

Fiat 500 PL

2007-2025 1.2L I4 Fire 69

Common Questions

What does code U0009 mean on a 2018-2025 Fiat Cronos?

U0009 stands for "High Speed CAN Communication Bus Shorted Together". CAN H and CAN L wires are shorted to each other, preventing differential signaling on the bus.

What are the symptoms of U0009 on a Fiat Cronos?

Common symptoms of U0009 include: Complete CAN bus failure, No communication with any module on bus, Vehicle may not start.

What causes U0009 on a 2018-2025 Fiat Cronos?

Common causes of U0009 include: CAN H and CAN L wires shorted together, Connector pin damage, Crushed wiring harness, Rodent damage to wiring.

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