P0113 means the signal from the intake air temperature sensor is above the range the engine computer considers plausible. The sensor may be reporting an impossibly high air temperature, or the circuit may simply be open, which is why a disconnected sensor and a failed one often set the same code. It is minor, but it does affect fuelling. Indicative UK repair cost is £20 to £150.
This is the cheapest fault in this library and one of the least dramatic. The sensor is a small thermistor measuring the temperature of the air entering the engine, and the computer uses it to trim the fuelling, because cold air is denser than warm air and needs more fuel to go with it. Get that figure wrong by a wide margin and the mixture drifts. Get it wrong by a little and almost nothing happens. One practical detail worth knowing before you go shopping: on a great many engines this sensor is built into the mass airflow sensor rather than being a separate part, so what looks like a cheap job can mean buying the more expensive component.
Can I drive with P0113?
Usually OK to drive, get it checked soon. Nothing is at risk here. The engine will fall back on a substitute air temperature value and carry on, and most people notice no difference at all. You might see slightly worse economy, or a marginally lumpier start on a very cold morning. The real reason to deal with it is that the warning light it has switched on will mask the next code to appear, and the next one may matter a great deal more than this one does.
What P0113 means for your MOT
Honest answer: the lamp, and realistically nothing else.
The DVSA MOT inspection manual treats a lamp that is on and indicating a malfunction as a major defect, in section 8.2.1.2 for petrol cars first used from 1 July 2003 and in section 8.2.2.2 for diesels first used from 1 July 2008. That is the route that will actually catch you.
There is a theoretical second route, because the measured emissions figures do move with fuelling and the air temperature reading is part of that calculation. In practice the correction this sensor applies is small, the test is carried out with the engine hot, and the substitute value the computer uses in its place is usually close enough that the gases stay inside the limits. So it would be overstating it to tell you the emissions test is at risk. Fix the lamp and the test takes care of itself.
What usually causes it
- A faulty sensor. Thermistors drift and fail with age and heat cycling. Where the sensor is a separate part this is a cheap item, and where it is integrated into the airflow sensor it is not.
- A disconnected or corroded connector. This belongs level with the first cause rather than below it. An open circuit reads as an implausible value, which is exactly what the code describes, and connectors in the intake area get knocked loose during air filter changes and other work in the same corner of the engine bay.
- A wiring fault. A chafed signal wire or a poor earth on the sensor circuit produces the same reading as a dead sensor. Less common than the two above, but it is the version that comes back after a new sensor has been fitted.
What it costs to fix in the UK
£20 to £150. A standalone sensor and ten minutes is the bottom. Reconnecting something that had worked loose is free. The top of the range is where the sensor is part of the airflow assembly and the whole unit has to be replaced, or where the fault is in the wiring and needs tracing.
On a fault this cheap, a garage diagnostic fee can genuinely exceed the repair, which is worth knowing before you book anything. What a car diagnostic costs in the UK sets out the going rate so you can make that call with your eyes open.
These are indicative UK ranges for guidance only. Actual causes and prices vary by vehicle, and a stored code points to a system, not always the exact part.
What to check first
- Find the sensor and check it is plugged in. Including whether it is integrated into the airflow sensor, which decides what the repair is going to cost. Look for a connector hanging free, a broken locking tab, or green deposits on the pins.
- Compare the reading against the actual air temperature. This is the free test and it is conclusive. On a car that has stood overnight, the intake air temperature on live data should read within a couple of degrees of the outside air. If it is reporting a figure nowhere near that on a cold engine, the sensor or its circuit is at fault and you have proved it without any equipment.
- Then check it again hot. Once the engine is warm the reading should rise above ambient, because the air is sitting in a hot engine bay. A figure that never moves at all is as informative as one that is wildly wrong.
- Wiggle the loom at the connector with the engine idling. A reading that jumps as you move the harness is wiring, and fitting a sensor will not fix it.
Related codes
- P0102, MAF sensor circuit low input. The page to read next if your air temperature sensor turns out to be built into the airflow sensor, because then the two codes share a part.
- P0128, coolant temperature below thermostat regulating temperature. The other temperature-reading fault, and a useful comparison because it is the one where the economy complaint is real.
- P0171, system too lean (Bank 1). Where a badly wrong air temperature reading can push the mixture, if the error is large enough.
Get it narrowed down before you spend
A stored code tells you which system is unhappy, not which part has failed. If you want it narrowed down before you spend anything, send the code and your symptoms and a mechanic will read them personally. Quick Diagnosis is £20, and if we can't help, you don't pay.
Written by the First Diagnostic mechanic. Over a decade in the trade: a VW-only workshop running diagnostics and electrical repair, then BMW-only through to full engine rebuilds. Now an independent all-makes workshop, plus building and wiring drift cars for competition, including trackside work as head mechanic. More about who reads your codes.