Air intake sensor error code P2003

[Minigirl]

Hi, my engine light was on and gave me fault code P2003 Air intake temperature sensor.

I cleared the fault (engine off) and the fault immediately came back without even starting the engine just the ignition on.

Started the car and it ran rough and horrible for 5 minutes then cleared up back to smooth running but still with engine light on and fault present

Does it sound like I need a new IAT sensor and should sort it or is there another known problem with the smart cars that it could be?

Thanks

[tolsen]

Does intercooler fan run continuously?
Mine does if I unplug.inlet air sensor. Engine control unit senses open circuit. You either have open circuit to sensor or faulty sensor. Remove sensor and test it with multimeter. Wiring most likely faulty if sensor tests out ok.
You can remove outside temperature sensor and plug in instead of IAT sensor and see if things improve.

[mottofreee]

Intake temperature sensor: http://www.fq101.co.uk/data-and-reference/59-sensors
It usually breaks the wires at the sensor. In this case, the intercooler fan always works as long as the engine is running.
IAT is located on the intercooler radiator at the CDI model or on the intake manifold for petrol models.
However, what smart car is it and with what device was this code found?
P0110 is the Smart Code for IAT connection failure.
IAT is classified as B17.
Code P2003 does not exist in the Smart CDI list.

[mottofreee]

I suggest a diagnosis with a serious device (eg MBStar). Of course, a technician with experience in handling diagnostics is needed. It matters to the technician to be a good acquaintance, age, sex, eye color does not matter at all .

[tolsen]

I wouldn’t mind a pretty buxom wench diagnosing my Smart.

[Minigirl]

I did it at work, should have grabbed the Mercedes Xentry and put that on it but this code reader was more convenient.

What sort of voltage should be going to the sensor?

[tolsen]

I guess 5 volt and current limited by a resistor. Power rating of thermistor in sensor is 60 mW.

[Minigirl]

I guess 5 volt and current limited by a resistor. Power rating of thermistor in sensor is 60 mW.

I stuck a voltmeter on the plug into pin 1 and pin 2 and it was reading 8volt

The fan runs all the time

Does it sound like a wiring problem?

Thanks

[tolsen]

Test your sensor. Its thermistor is same as coolant temperature sensor and outside temperature sensor. Also same socket.

You can change thermistor but must use clamp heat sink when soldering.
Info in below thread dealing with outside temperature sensor.

http://smartmaniacs.co.uk/forum/the-...e-sensor/page3

[tolsen]

Link to RS Components if you wish to replace thermistor:

https://uk.rs-online.com/mobile/p/thermistors/5288508/

[tolsen]

About soldering in thermistors.

Speed of soldering is essential. Clean the pins on sensor housing and wet these with solder first. Solder on each thermistor leg making sure to clamp heat sink between solder point and thermistor bead. For heat sink I simply use a small crocodile clamp, the type that plugs into the tip of your multimeter lead.

[Minigirl]

Thanks i have tried the front air temperature sensor in place of the manifold temperature sensor and the intercooler fan still runs non stop about 5 seconds after the engine starts

Is this indicating a wiring problem?

With the engine running I connected the multimeter probe to pin 1 and the other to earth and it read 14 volts. I then connected it to pin 2 and the other to earth and it read 3.8 volts

I cleaned the main earth from the chassis to the exhaust mount and the earth's above the intercooler. The main battery earth looks clean and new

[tolsen]

I have now concluded IAT has different thermistor to outside temperature sensor.

Plugging in outside temperature sensor in lieu of IAT sensor gives far too low resistance.
ECU therefore gets fooled to believe temperature is very high and switches on intercooler fan.

Measure resistance of your IAT sensor. It is most likely faulty.

[tolsen]

Have just plugged IAT sensor into outside temperature sensor plug. With IAT temperature readout was 9C. 20C with outside temperature sensor. I also plugged in a coolant temperature sensor and read 22C.
Then tried coolant temperature sensor in IAT position. Intercooler fan did not run for me but that does not mean much. Of course Scottish weather up here not particularly warm.
Fan turned on when running engine without any sensor.

[Minigirl]

I think I have found the problem... Someone has connected the IAT plug to the clean air switching valve and Im guessing the clean air switching valve plug to the IAT sensor....

The plug going to the switching valve had 53 and 17 on the wires which is for the IAT sensor going by the Evilution pin out list.

The wires on the IAT had 65 and 127 on them

Havent switched them yet just want to make sure this sounds correct that the plug going to the switching valve has 65 and 127 on them

Thanks

[tolsen]

Hope nothing has burnt out inside ECU.