OBD Guide

P04B8

Fuel Fill Door Position Sensor/Switch Circuit

P04B8 is an OBD-II diagnostic trouble code meaning: Fuel Fill Door Position Sensor/Switch Circuit. Common causes: cover position sensor/switch malfunction, open or shorted wiring harness. Estimated repair cost: $22–89.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$22–89 (est.)

Symptoms

  • Check Engine Light Is On
  • Error when checking the tightness of the EVAP system
  • Possible problems with fuel refueling

Causes

  • Cover position sensor/switch malfunction
  • Open or shorted wiring harness
  • Poor contact in the sensor connector
  • Mechanical damage to the fuel tank cap
  • Problems with the engine control unit

How to Fix

  1. Visual inspection of the fuel tank cap and sensor
  2. Checking the integrity of the wiring harness and contacts
  3. Testing the sensor with a multimeter
  4. Replacing a faulty sensor or cover
  5. Clearing error codes and checking the system

Related codes

Error P04B8 by Vehicle Brand

FAQ

What does the P04B8 code mean?

P04B8 is an OBD-II diagnostic trouble code that indicates: Fuel Fill Door Position Sensor/Switch Circuit

What causes a P04B8 error code?

The most common causes of P04B8 include: Cover position sensor/switch malfunction; Open or shorted wiring harness; Poor contact in the sensor connector; Mechanical damage to the fuel tank cap.

How do I fix a P04B8 diagnostic trouble code?

To fix P04B8: Visual inspection of the fuel tank cap and sensor. Checking the integrity of the wiring harness and contacts. Testing the sensor with a multimeter. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P04B8?

Yes, but get it checked soon

How much does it cost to fix P04B8?

The estimated repair cost for P04B8 is $22–89. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat