OBD Guide
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P111B

Mass or Volume Air Flow via O2 Sensor Too Low Bank 1

P111B is an OBD-II diagnostic trouble code meaning: Mass or Volume Air Flow via O2 Sensor Too Low Bank 1. Common causes: vacuum leaks in the intake tract, dirty or faulty mass air flow sensor (maf). Estimated repair cost: $17–67.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$17–67 (est.)

Symptoms

  • Unstable engine idling
  • Reduced engine power
  • Increased fuel consumption
  • Check Engine Light Is On
  • Dips during acceleration

Causes

  • Vacuum leaks in the intake tract
  • Dirty or faulty mass air flow sensor (MAF)
  • Oxygen (O2) sensor malfunction
  • Clogged air filter
  • O2 Sensor Harness Problems

How to Fix

  1. Check the intake system for vacuum leaks
  2. Clean or replace the mass air flow sensor (MAF)
  3. Check and, if necessary, replace the oxygen sensor of bank 1
  4. Replace the air filter if it is dirty
  5. Check the integrity of the O2 sensor wiring harness

Related codes

P111AP111CP112B

FAQ

What does the P111B code mean?

P111B is an OBD-II diagnostic trouble code that indicates: Mass or Volume Air Flow via O2 Sensor Too Low Bank 1

What causes a P111B error code?

The most common causes of P111B include: Vacuum leaks in the intake tract; Dirty or faulty mass air flow sensor (MAF); Oxygen (O2) sensor malfunction; Clogged air filter.

How do I fix a P111B diagnostic trouble code?

To fix P111B: Check the intake system for vacuum leaks. Clean or replace the mass air flow sensor (MAF). Check and, if necessary, replace the oxygen sensor of bank 1. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P111B?

Yes, but get it checked soon

How much does it cost to fix P111B?

The estimated repair cost for P111B is $17–67. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat