Officially? A wall of jargon. To most people? Absolutely nothing. That's exactly why we built the app.
Plug into any code reader and you'll get the same line every other app shows you. Technically correct. Practically useless.
"Your engine's telling you it's running too lean on bank 1 — too much air for the fuel it's getting — and it's had to add fuel to compensate. The classic cheap cause is unmetered air sneaking in past the mass airflow sensor: a split intake hose, a loose or perished breather, or a leaking gasket. A dirty MAF sensor is another common and cheap one. Weak fuel delivery (filter, pump or injectors) is possible but usually further down the list. If you also see P0174, that points squarely at something both banks share — a vacuum leak or the MAF — rather than one dodgy injector."
Worth checking in roughly this order. Don't jump straight to the expensive fix:
The code itself is a snapshot. The fault sets after the car's watched the numbers over a whole drive cycle. Here's what's worth keeping an eye on:
Illustrative panels. These readings aren’t in our free demo drive, but the app shows them live from your own car.
Codes rarely tell the whole story. The clever part is reading them together, and against your exact car. Here's the kind of thing it catches:
Your engine's telling you it's running too lean on bank 1 — too much air for the fuel it's getting — and it's had to add fuel to compensate. The classic cheap cause is unmetered air sneaking in past the mass airflow sensor: a split intake hose, a loose or perished breather, or a leaking gasket. A dirty MAF sensor is another common and cheap one. Weak fuel delivery (filter, pump or injectors) is possible but usually further down the list. If you also see P0174, that points squarely at something both banks share — a vacuum leak or the MAF — rather than one dodgy injector.
Short term, yes — but don't leave it. A lean mixture runs the engine hotter and, left long enough, can cause rough idling, hesitation and eventually damage. If it's just idling rough it's not urgent, but get the leak sorted before it starts affecting how it drives.
Often very little. A vacuum hose or a can of MAF cleaner is a few quid, and many people fix this themselves. If it's a failed MAF sensor you're looking at maybe £50-150 fitted. A fuel pump or injectors would be the expensive end, but that's less common for this code.
Not with the engine light on — that's been an automatic MOT fail in the UK since 2018. A lean-running engine can push up emissions too, so the tailpipe test is also at risk. Best to fix it beforehand — it's usually cheap anyway.
Free app. Plug in, and get every code in plain English, plus the connections you'd never spot.