← View Generic P0171 Guide Severity: Medium
🚗 Vehicle-Specific Guide

This guide is customized for your 2025 Mercedes Benz CLA45 AMG S

P0171: System Too Lean Bank 1

on 2025 Mercedes Benz CLA45 AMG S

Fix Cost
$30 - $300
Parts & Labor
Difficulty
3/5
1-3 hours
DIY Possible?
✅ Yes
Save money
Your Vehicle
2025 Mercedes Benz
CLA45 AMG S
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Important for 2025 Mercedes Benz CLA45 AMG S Owners

Before starting repairs, verify which engine your 2025 Mercedes Benz CLA45 AMG S has. Check your VIN or engine code to ensure you order the correct parts.

📖 What Does P0171 Mean on 2025 Mercedes Benz CLA45 AMG S?

The engine is running with too much air and not enough fuel on bank 1. The oxygen sensor is detecting a lean fuel mixture, and the engine control module cannot compensate adequately.
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Symptoms

  • • Rough idle
  • • hesitation during acceleration
  • • lack of power
  • • backfiring
  • • hard starting
  • • check engine light
  • • poor fuel economy.
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Common Causes

  • • Vacuum leaks
  • • faulty mass airflow sensor
  • • clogged fuel injectors
  • • weak fuel pump
  • • dirty air filter
  • • faulty fuel pressure regulator
  • • intake manifold gasket leak.
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How to Fix P0171 on 2025 Mercedes Benz CLA45 AMG S

Find and repair vacuum leaks, clean or replace mass airflow sensor, clean fuel injectors, test and replace fuel pump if needed, replace air filter, check fuel pressure regulator.

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Need Maintenance Info for Your CLA45 AMG S?

Get oil capacity, filter specs, and torque settings for your specific 2025 Mercedes Benz CLA45 AMG S.

View 2025 Mercedes Benz CLA45 AMG S Specs

Parts for 2025 Mercedes Benz CLA45 AMG S

MAF Sensor Shop ↗ Fuel Filter Shop ↗ Vacuum Hoses Shop ↗ Fuel Injector Cleaner Shop ↗

Essential Tool

Must Have

OBD2 Scanner

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Related Diagnostic Codes

Other codes that may appear with P0171

P0174 Same System

System Too Lean Bank 2

Medium
P0301 Related Problem

Cylinder 1 Misfire Detected

High
P0302 Related Problem

Cylinder 2 Misfire Detected

High
P0303 Related Problem

Cylinder 3 Misfire Detected

High
P0304 Related Problem

Cylinder 4 Misfire Detected

High
P0420 Related Problem

Catalyst System Efficiency Below Threshold Bank 1

Medium

💡 Why These Codes Are Related:

  • • Similar Issues: Same root cause or component failure
  • • Related Problems: Often occur together due to system interactions
  • • Sequential Codes: Progressive failure stages or multiple sensors
  • • Same System: Components within the same automotive system