OBD Guide

B3749

Air Flow Control 7 Feedback Circuit Performance

B3749 is an OBD-II diagnostic trouble code meaning: Air Flow Control 7 Feedback Circuit Performance. Common causes: malfunction of the mass air flow sensor (maf), wiring harness damage. Estimated repair cost: $56–167.

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

Symptoms

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

Causes

  • Malfunction of the mass air flow sensor (MAF)
  • Wiring harness damage
  • Engine control unit malfunction
  • Throttle valve contamination

How to Fix

  1. Check the mass air flow sensor (MAF)
  2. Inspect the wiring harness for damage
  3. Check the operation of the engine control unit
  4. Clean throttle body

Related codes

Error B3749 by Vehicle Brand

FAQ

What does the B3749 code mean?

B3749 is an OBD-II diagnostic trouble code that indicates: Air Flow Control 7 Feedback Circuit Performance

What causes a B3749 error code?

The most common causes of B3749 include: Malfunction of the mass air flow sensor (MAF); Wiring harness damage; Engine control unit malfunction; Throttle valve contamination.

How do I fix a B3749 diagnostic trouble code?

To fix B3749: Check the mass air flow sensor (MAF). Inspect the wiring harness for damage. Check the operation of the engine control unit. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with B3749?

Limited driving only, diagnose soon

How much does it cost to fix B3749?

The estimated repair cost for B3749 is $56–167. Actual cost depends on your vehicle, location, and labor rates.

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