OBD Guide
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U18A7

Lost Communication With Power Supply Transformer On Powertrain Expansion CAN Bus

U18A7 is an OBD-II diagnostic trouble code meaning: Lost Communication With Power Supply Transformer On Powertrain Expansion CAN Bus. Common causes: broken or damaged wires in the can circuit, power transformer fault. Estimated repair cost: $56–167.

Severity
🔴 High
Can you drive?
Do not drive — repair immediately
Approx. repair cost
$56–167 (est.)

Symptoms

  • Unstable engine operation
  • Gear shifting problems
  • Check Engine Light Illuminates
  • Reduced vehicle power
  • Errors in other CAN bus-related systems

Causes

  • Broken or damaged wires in the CAN circuit
  • Power transformer fault
  • Transformer power problems
  • Short circuit in the circuit
  • ECU malfunction

How to Fix

  1. Check the integrity of wires and connections in the CAN circuit
  2. Diagnose power transformer
  3. Check the voltage on the transformer
  4. Replacing the power transformer if necessary
  5. Check and, if necessary, replace the computer

Related codes

U18A6U18A8U18A9

FAQ

What does the U18A7 code mean?

U18A7 is an OBD-II diagnostic trouble code that indicates: Lost Communication With Power Supply Transformer On Powertrain Expansion CAN Bus

What causes a U18A7 error code?

The most common causes of U18A7 include: Broken or damaged wires in the CAN circuit; Power transformer fault; Transformer power problems; Short circuit in the circuit.

How do I fix a U18A7 diagnostic trouble code?

To fix U18A7: Check the integrity of wires and connections in the CAN circuit. Diagnose power transformer. Check the voltage on the transformer. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with U18A7?

Do not drive — repair immediately

How much does it cost to fix U18A7?

The estimated repair cost for U18A7 is $56–167. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat