OBD Guide
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P120B

Secondary Fuel Injector Bank 1 Excessive Flow

P120B is an OBD-II diagnostic trouble code meaning: Secondary Fuel Injector Bank 1 Excessive Flow . Common causes: secondary fuel injector malfunction, problems with the injector electrical circuit. Estimated repair cost: $28–89.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$28–89 (est.)

Symptoms

  • Increased fuel consumption
  • Reduced engine power
  • Rough engine idling
  • Smell of gasoline from the exhaust pipe
  • Check Engine light comes on

Causes

  • Secondary fuel injector malfunction
  • Problems with the injector electrical circuit
  • Engine control unit malfunction
  • Dirty or clogged injector
  • Mechanical damage to the fuel system

How to Fix

  1. Check the injector electrical circuit for opens and shorts
  2. Test injector resistance and performance
  3. Clean or replace the faulty injector
  4. Check the pressure in the fuel system
  5. Reset the error code and test drive

Related codes

P120AP120CP120D

FAQ

What does the P120B code mean?

P120B is an OBD-II diagnostic trouble code that indicates: Secondary Fuel Injector Bank 1 Excessive Flow

What causes a P120B error code?

The most common causes of P120B include: Secondary fuel injector malfunction; Problems with the injector electrical circuit; Engine control unit malfunction; Dirty or clogged injector.

How do I fix a P120B diagnostic trouble code?

To fix P120B: Check the injector electrical circuit for opens and shorts. Test injector resistance and performance. Clean or replace the faulty injector. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P120B?

Yes, but get it checked soon

How much does it cost to fix P120B?

The estimated repair cost for P120B is $28–89. Actual cost depends on your vehicle, location, and labor rates.

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