OBD Guide

U3018

Control Module Input Power Circuit A/B Correlation

U3018 is an OBD-II diagnostic trouble code meaning: Control Module Input Power Circuit A/B Correlation. Common causes: poor contact in the control unit connectors, open or short circuit in wiring harness. Estimated repair cost: $6–167.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$6–167 (est.)

Symptoms

  • Unstable engine operation
  • Intermittent failures of electronic systems
  • Check Engine light comes on
  • Problems starting the engine

Causes

  • Poor contact in the control unit connectors
  • Open or short circuit in wiring harness
  • Faulty relays or fuses
  • Alternator or battery problems
  • Malfunction of the control unit itself

How to Fix

  1. Check the condition of the battery and generator
  2. Inspect the wiring harness and connectors of the control unit
  3. Check relays and fuses of relevant circuits
  4. Measure voltages on power circuits A and B
  5. If necessary, replace the control unit

Related codes

Error U3018 by Vehicle Brand

FAQ

What does the U3018 code mean?

U3018 is an OBD-II diagnostic trouble code that indicates: Control Module Input Power Circuit A/B Correlation

What causes a U3018 error code?

The most common causes of U3018 include: Poor contact in the control unit connectors; Open or short circuit in wiring harness; Faulty relays or fuses; Alternator or battery problems.

How do I fix a U3018 diagnostic trouble code?

To fix U3018: Check the condition of the battery and generator. Inspect the wiring harness and connectors of the control unit. Check relays and fuses of relevant circuits. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with U3018?

Yes, but get it checked soon

How much does it cost to fix U3018?

The estimated repair cost for U3018 is $6–167. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat