OBD Guide
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U1800

Lost Communications With Fuel Injector Control Module

U1800 is an OBD-II diagnostic trouble code meaning: Lost Communications With Fuel Injector Control Module. Common causes: open or short circuit in the communication circuit, faulty injector control module. Estimated repair cost: $56–167.

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

Symptoms

  • The engine stalls or does not start
  • Loss of engine power
  • Increased fuel consumption
  • Check Engine Light Is On
  • Rough engine idling

Causes

  • Open or short circuit in the communication circuit
  • Faulty injector control module
  • Wiring Harness Problems
  • Corrosion of contacts or connectors
  • Software error in the ECU

How to Fix

  1. Check the integrity of the wiring harness and connectors
  2. Check the voltage and resistance in the communication circuit
  3. Scan the ECU for other errors
  4. Replace the injector control module if necessary
  5. Update ECU firmware

Related codes

U1801U1802U0100

FAQ

What does the U1800 code mean?

U1800 is an OBD-II diagnostic trouble code that indicates: Lost Communications With Fuel Injector Control Module

What causes a U1800 error code?

The most common causes of U1800 include: Open or short circuit in the communication circuit; Faulty injector control module; Wiring Harness Problems; Corrosion of contacts or connectors.

How do I fix a U1800 diagnostic trouble code?

To fix U1800: Check the integrity of the wiring harness and connectors. Check the voltage and resistance in the communication circuit. Scan the ECU for other errors. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with U1800?

Do not drive — repair immediately

How much does it cost to fix U1800?

The estimated repair cost for U1800 is $56–167. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat