General Intake Air Temp constant 419F reading

[skyman191]

Hi all,


Any help appreciated.

I have a Ducato 3.0 160 Multijet 2008, its giving a Mil light and showing the following code.
Code P0111 Intake Air Temperature Sensor 1 Circuit Range/Performance.

The intake air temperature reads a constant 419F, new MAF and MAP fitted, wiring checked.


Thanks

 

[rayc]

I know little of these things but my experience in industry where circuits are monitored constantly is to check the sensor as part of initial investigation.
http://www.obd-codes.com/p0111

 

[CDK]

The MAP sensor measures both pressure and temperature. 419F is way out of range, hence the P0111 error code.
Possible causes are a wrong sensor type or a damaged contact in the sensor plug.

 

[skyman191]

Thanks for the replies, as stated both the MAP and MAF have been replaced.
The vehicle shows a reading for intake temp of 417F with ignition on and engine not running, even with the MAP sensor unplugged.


My understanding is that the Air Intake Temperature is measured by both MAF and MAP sensors working together.
I am thinking that it is more likely an ECU issue and was hoping that someone may have answers following a similar experience.


Thanks

 

[Crossingkeeper]

I've not had 'hands on' experience of this particular issue so this is by way of a general observation:

Temperature sensors usually work on the principle of changing resistance with temperature and the display or receiver measures the resultant voltage drop: simplistically 12 volts will be fed in one side of the [MAP] sensor and 0-12 volts will come out the other side, though in practice it is probably wired differently to this.

I'd guess that 417F is probably the maximum value anticipated for intake temperature? If so this suggests the measured voltage is either minimum or maximum value which in turn suggests the wiring to/from the sensor is open circuit. (confirmed by you getting a reading of 417F with MAP sensor unplugged)

As CDK suggested it could equally well be a bad contact in a multiplug.

 

[Deefordog]

Out of interest, what make of MAF was fitted?


I've had bad experiences by fitting cheap MAF sensors off Ebay and have ended up fitting Bosch ones - problems solved.

 

[CDK]

"The vehicle shows a reading for intake temp of 417F with ignition on and engine not running, even with the MAP sensor unplugged."

Although not entirely impossible, an ECU failure is highly unlikely.
There are MAP sensors with and without a temperature sensor, identical casings. And a contact in the tiny connector can be damaged, so even with the connector installed, no current flows.
Check the voltage between the pins and ground, it should be approx. 5 VDC.