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.
"The intake air temperature sensor is reporting an impossibly cold reading — the 'circuit high' bit means the signal wire is seeing high voltage, which the ECU reads as something like minus 40. Real air is never that cold, so this is an electrical fault, not a temperature problem: a broken wire, a corroded or unplugged connector, or the sensor itself gone open-circuit. On most cars the IAT lives inside the MAF sensor or in the intake pipe near the air box, so start with a look at that plug — this is one of the easiest codes to chase."
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:
The intake air temperature sensor is reporting an impossibly cold reading — the 'circuit high' bit means the signal wire is seeing high voltage, which the ECU reads as something like minus 40. Real air is never that cold, so this is an electrical fault, not a temperature problem: a broken wire, a corroded or unplugged connector, or the sensor itself gone open-circuit. On most cars the IAT lives inside the MAF sensor or in the intake pipe near the air box, so start with a look at that plug — this is one of the easiest codes to chase.
Yes. The ECU substitutes a sensible default temperature when the sensor's talking rubbish, so the car runs close to normal — maybe marginally worse economy or slightly hesitant cold starts. It's a fix-at-your-convenience fault, not a stop-driving one.
Cheap as codes come. A standalone IAT sensor is often £10-25 and plugs in by hand. If it's built into the MAF and the MAF needs replacing, that's more like £40-150. If it's just a grotty connector, the fix costs nothing but ten minutes.
Not with the engine light showing — an illuminated engine management light has been an automatic MOT fail in the UK since 2018. Fortunately this is about the cheapest, easiest category of fault to put right before the test.
Free app. Plug in, and get every code in plain English, plus the connections you'd never spot.