OBD Guide

P0178

Fuel Composition Sensor Circuit Low

P0178 is an OBD-II diagnostic trouble code meaning: Fuel Composition Sensor Circuit Low. Common causes: fuel composition sensor malfunction, open or short circuit in the sensor circuit. Estimated repair cost: $56–167.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$56–167 (est.)

Symptoms

  • Check Engine light comes on
  • Reduced engine power
  • Increased fuel consumption
  • Unstable engine idling

Causes

  • Fuel composition sensor malfunction
  • Open or short circuit in the sensor circuit
  • Poor contact in the sensor connector
  • Problems with the ECU

How to Fix

  1. Check the continuity of the fuel composition sensor circuit
  2. Inspect the sensor connector for corrosion or damage.
  3. Replace the fuel composition sensor if necessary
  4. Check the operation of the computer

Related codes

Error P0178 by Vehicle Brand

FAQ

What does the P0178 code mean?

P0178 is an OBD-II diagnostic trouble code that indicates: Fuel Composition Sensor Circuit Low

What causes a P0178 error code?

The most common causes of P0178 include: Fuel composition sensor malfunction; Open or short circuit in the sensor circuit; Poor contact in the sensor connector; Problems with the ECU.

How do I fix a P0178 diagnostic trouble code?

To fix P0178: Check the continuity of the fuel composition sensor circuit. Inspect the sensor connector for corrosion or damage.. Replace the fuel composition sensor if necessary. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P0178?

Limited driving only, diagnose soon

How much does it cost to fix P0178?

The estimated repair cost for P0178 is $56–167. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat