OBD Guide
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P1151

Lack Of HO2S21 Switch - Sensor Indicates Lean

P1151 is an OBD-II diagnostic trouble code meaning: Lack Of HO2S21 Switch - Sensor Indicates Lean. Common causes: vacuum leak, oxygen sensor malfunction (ho2s21). Estimated repair cost: $17–67.

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

Symptoms

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

Causes

  • Vacuum leak
  • Oxygen sensor malfunction (HO2S21)
  • Problems with the fuel pump or injectors
  • Sensor wiring harness is dirty or damaged
  • Air intake system malfunction

How to Fix

  1. Check for vacuum leaks
  2. Check the condition of the oxygen sensor and its wiring harness
  3. Check the operation of the fuel pump and injectors
  4. Clean or replace the oxygen sensor if necessary
  5. Check the air intake system for blockages

Related codes

P1130P1131P1150

Error P1151 by Vehicle Brand

BMWFordLincolnMazdaMercurySubaruVolkswagen

FAQ

What does the P1151 code mean?

P1151 is an OBD-II diagnostic trouble code that indicates: Lack Of HO2S21 Switch - Sensor Indicates Lean

What causes a P1151 error code?

The most common causes of P1151 include: Vacuum leak; Oxygen sensor malfunction (HO2S21); Problems with the fuel pump or injectors; Sensor wiring harness is dirty or damaged.

How do I fix a P1151 diagnostic trouble code?

To fix P1151: Check for vacuum leaks. Check the condition of the oxygen sensor and its wiring harness. Check the operation of the fuel pump and injectors. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P1151?

Yes, but get it checked soon

How much does it cost to fix P1151?

The estimated repair cost for P1151 is $17–67. Actual cost depends on your vehicle, location, and labor rates.

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