I've seen one other E3 code thread on this forum. It's from 2010. https://www.ferrarichat.com/forum/threads/e3-code-on-a-climate-control-unit.269323/ I had my HVAC throw the E3 code, and what luck!!! ebay had a new sensor, so i nabbed it. ($50???!!!! c'mon) The old sensor is located under the passenger dash in a fairly easy to access area above the footwell, pictured below, in white. Press on the tab next to where the wires go in, wiggle a little and it comes free. The sensor is only straight snapped in to place, you just grab it and pull. (see below) Image Unavailable, Please Login The sensor is just pressed in to place, and there's a ring of black RTV around it. It's shown below with the remains of the blob of RTV intact, but the halves split open. Image Unavailable, Please Login The replacement looks like this (the ball shape before the block on the left is a set of molded snaps. Image Unavailable, Please Login I took the old one out, and measured each of them. The bad one measured 0 Ohms...so with the new one in place and working, I decided to do a little engineering investigation, and open the casing. It's only snapped together. The block end has two big snaps (If you reference the two pictures above this, you can see how it separates. Lo and behold! The tiny wires inside had a solder joint break. (Does this lend a data point to the crimp vs solder thread?) Note there was potting on both sides, but the side without had it stuck in the upper half. Image Unavailable, Please Login I put it back together with a dab of solder so bad it reminds me to buy a new soldering rig (not pictured). It works though!! Resistance restored, and changes under the hot breath test on a meter. Plugging in to the car shows no more E3 error, and now I have a spare. As the bard would say: There you have it, another DIY thread, and one less mystery. sjd
As a note, I DID do the "check all the connections and clean" step before delving into the sensor...but as relatively easy as the sensor was to check, just check the sensor with a meter. If it reads open on resistance...it's likely a broken wire. sjd
Looks like the "treated air sensor" Part number 63307000? (Item 13)? https://www.ricambiamerica.com/car-diagrams/ferrari/v6-v8/355-group/f355-m2-7-1995/evaporator-unit-and-passengers-compartment-aeration.html Looking at your last photo, the break seems to be a few inches from the soldered terminal. Did you resolder the wire at the break? I assume the whole length of the wire is the sensing element (because there are holes along the entire length of the sensor and the wires don't have any insulation). The wire may be made of a special negative temperature coefficient (NTC) metal. I assume a solder joint at this point should not affect the resistance too much. Some types of temperature sensors use two wires made of dissimilar metals, and for this "thermocouple" type, I don't know what effect it would have if you soldered the break with a 3rd type of metal (solder). https://www.quora.com/What-is-the-main-function-of-a-thermocouple The WSM says the HVAC sensors are the NTC type, but I didn't think NTC types had a "bulb" as shown in your photo. Just wondering why the wire would break at this point.
The wire is not broken. The solder joint broke. Here's a closeup of the other side. This is how they are?....or someone has fixed this one once already. The only way to know is to crack the other one open, which was an open box NOS part. IMO, judging by the overlap you can see as the slightly darker grey of the loose end in the picture below, they're soldered... Image Unavailable, Please Login
Thanks. Strange design. Perhaps the sensing element has to be a certain length to get the right resistance values (although you would think that the electronics in the ECU could compensate for that)
