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turbines
10-06-2014, 06:38 PM
I bought a 2006 Roadtrek that had been in extended storage for about 6 years. It runs great but the Check Engine codes a "intake temp sensor" problem intermittent. If reset it may stay off for 3 or maybe sometimes 30 miles before illuminating again. I took the MAF and duct sensor plugs loose and cleaned thoroughly but that was no help. I took it the MB Sprinter Service Center and they charged me $125 to erase the code again and sent me on my way. The light came back on again before getting home. Anyone have a plan that might resolve this issue?

johnshmit
10-06-2014, 07:18 PM
That is a $20 sensor on a charge air hose between intercooler and EGR valve.

http://europarts-sd.com/intakeairtemperaturesensor2002-2009.asp

jmoller99
10-07-2014, 02:08 PM
The part is essantially a resistor that changes its resistance when the termperature changes. It is used in conjunction with the Ambiant Air sensor (right behind the front license plate mount - on the front bumper; I know not everyone is required to have a front plate, however, that is where the sensor is located).

The Computer uses these temperature measurements to determine if the boosted pressure is within a temperature range that is safe for the engine operation, and if something is out of the ranges it throws an error. It also uses the boost pressure, MAP and Mass Air Flow (MAF) readings to make sure that everything adds up to what it expects. If any sensor is not working right, you might get an error, or the Turbo may go into LHM. Air Leaks are easy to detect with these parameters sent to the Computer - It would be nice if it actually told you which parameter threw you into LHM - that is not how the Computer throws P-Codes, but that is another discussion.

On my 2002, I monitor the Boost pressure, MAP and Air Intake temp, as well as set my console to tell me outside temperature (ambiant air temp) instead of showing a clock - My radio has a clock already, I don't need 2 clocks. I use an UltraGuage EM (but a ScanGuage II would work fine too). My Air intake (after the turbo air goes thru the intercooler) is generally at least 10 degrees F higher than the Ambiant Air temp (degrees F). It sometimes is 45+ degrees hotter than ambiant air temps.

When I got my 2002, I would have random turbo shut downs. I put in the UltraGuage EM only to find that my Air intake sensor was reading high - occasionally it would spike at 300 degress F and my turbo would shut off (obvioulsy - this is way out of safe range, and if true, there is a serious problem). In actuality, it was a bad air intake sensor (about $20 to replace - I now carry a spare with me). You might want to replace yours (its pretty easy - it is on the plastic hose/bracket adapter that the rubber turbo hose that goes into the engine intake manafold connects to; there are 2 sensors there). I would get some automotive spray electrical contact cleaner and use it to clean up the connector at the same time - I have had a lot of poor electrical connections in the connectors in the engine compartment over the years where the sensor was fine, but not making good contact.

In my case, the Air Intake sensor would go 'open' occasionally - no real pattern, it just did it. A lot of people have had similar issues.

You may want to invest in a ScanGauge II or an UtraGuage EM (or something like these) to monitor the turbo operations while you drive (they plug into the ODBII port). The ScanGuage II can reset some errors.