Uploaded April 2026 | Updated September 2026, 21 hours ago
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Engine running lean (P0171/P0174)? Learn what a lean condition means, the most common symptoms, and the real causes—vacuum leaks, dirty MAF sensor, low fuel pressure, clogged injectors, exhaust leaks before the O2 sensor, and PCV problems. Mechanic-style guidance on how to diagnose fuel trims, what to check first, and how to fix a lean mixture before it damages your engine or catalytic converter.
Timecode:
00:00:00 - Short intro
00:00:35 - How you know it’s running lean
00:01:36 - Cause 1
00:02:27 - Cause 2
00:03:10 - Cause 3
00:03:49 - Cause 4
00:04:33 - Cause 5
00:05:10 - Cause 6
00:05:40 - Cause 7
00:06:15 - What you should check first to save time and money
youtube.com/@carproblemsmax/join - Become our Sponsor
Engine running lean (P0171/P0174)? Learn what a lean condition means, the most common symptoms, and the real causes—vacuum leaks, dirty MAF sensor, low fuel pressure, clogged injectors, exhaust leaks before the O2 sensor, and PCV problems. Mechanic-style guidance on how to diagnose fuel trims, what to check first, and how to fix a lean mixture before it damages your engine or catalytic converter.
Timecode:
00:00:00 - Short intro
00:00:35 - How you know it’s running lean
00:01:36 - Cause 1
00:02:27 - Cause 2
00:03:10 - Cause 3
00:03:49 - Cause 4
00:04:33 - Cause 5
00:05:10 - Cause 6
00:05:40 - Cause 7
00:06:15 - What you should check first to save time and money
