Ambient Air Temperature Sensor Cylinder Bank 2

I believe the MAF (mass air flow) meter (228396) most likely has an intake air temperature (IAT) sensor incorporated into it. I believe this is normal practice in modern air intake systems. I cannot see any other logical location for an ambient air temperature sensor specific to one bank of the engine’s cylinders. However I would check before buying the part because it isn’t cheap.

If you can’t get information on the part you could also swap the Bank 1’s MAF with the unit on Bank 2 and see if the error changes to indicate the problem is now on Bank 1.

 

Thanks for the update but I think the "little nipple" sensor you refer to is the wrong one.

I don't know who told you about it but according to the P0074 error, this is almost certainly not the temperature sensor involved. I know the sensor you found is much cheaper but cannot trigger a P0074 because it has nothing to do with the engine. Correct me if I am wrong but the sensor you appear to be referring to is this one (below).

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It's part 236847 (see supplier websites), which is also used to determine ambient temperature in the passenger compartments (dashboard) and AC systems of many contemporary Ferraris. However, your "P0074 - Ambient Air Temperature Sensor Cylinder Bank 2" is specific for cylinder bank 2 (air intake) and there is no way for the sensor on the Cali's wing mirror to determine the temperature of air reaching each of the 2 banks of cylinders in your engine. FWIW, there can also be significant differences in air temperature at the wing mirror compared to the air intake which starts at the front grill and is affected by the hot engine compartment before the air gets to the cylinders.

In addition, there is ONLY ONE 236847 used on the Cali's wing mirrors - only the driver's side mirror has one. IMO, it's used to assist the climate control system in conjunction with the 236847 used inside the car (see below). There is no way for one sensor to determine the difference in ambient temperature between Bank 1 and Bank 2 of cylinders in the engine. Any sensor for that function needs to be in-line with the air intake system to the banks of cylinders - hence, each MAF has one.

The MAF collects ambient temperature data to assist the engine ECU to determine ignition timing for each bank of cylinders. A sensor on one wing mirror can never accomplish that.

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I looked up the P0074 error code.

While you may have indeed found the problem the error code description you provided appears to be misleading because P0047 is a generic OBDII code and it actually stands for "P0074 – Outside air temperature sensor -circuit intermittent" and not "P0074 - Ambient Air Temperature Sensor Cylinder Bank 2". The P0074 error code has nothing to do with engine management.

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Where did you get the "P0074 - Ambient Air Temperature Sensor Cylinder Bank 2" message description? As you see from the above link and screenshot. it is the IAT that is used for engine management. I think someone/something gave you the wrong description for P0074. P0074 affects passenger compartment (air conditioner) climate control.

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OTOH, here is a description of the IAT. You can easily find more information on the Web on the IAT and MAF.

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OBDII errors for the IAT are covered under the following codes and you can find explanations HERE:

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So, I think the error code you posted was confused. It probably was a P0074 but it did not concern "Ambient Air Temperature Sensor Cylinder Bank 2" which would (most likely) have been P00AA or P00AE.

I am providing these explanations so other readers won't get confused to think the little sensor on their mirrors affect engine management - it doesn't. If it did its location would be inadequate, inappropriate and also overly vulnerable to compromise for it to provide important engine management data.

 

Which OBD2 reader are you using? It is obviously giving you the a mixed-up code... the code number is probably correct but if so the text is then wrong.

I used to design and code automation and robotic controller software for major western companies back in the days when such software only came from the US, Canada or western Europe. The error code descriptions given by OBD2 readers are just English text that some gofer at a software firm typed in. The test is not "gospel". Such tasks are usually assigned to low-skilled staff as the higher-skilled staff will code, design software or even write specifications relating to software architecture. The text can easily be erroneous if not properly-checked. Most of these OBD2 readers are made in CHINA.

At any rate, you cannot use data on air temperatures collected from under the wing mirror to run your engine. The information I quoted above pertains to ordinary cars so you can imagine how bad it would look if Ferrari manages its engines using data normally meant for running the AC in the passenger compartment.

 

Actually, that little temperature sensor on the bottom of the mirror is the ambient (outside air) temperature sensor, and is used for both the climate control and engine management systems. If it did not provide information to the engine management system, it would not cause an OBDII Fault.

Brian Brown
San Francisco Motorsports

 

With all due respect, your comment is misleading. You restate a fact that I already stated, while also contradicting the multiple external sources I quoted by making an assumption that all these sources already disproved.

I already indicated the AAT on the mirror does input to the PCM. One of the links I provided also says the PCM may flag a OBD2 fault as a result. You alluded to this and restated this in your own fashion.

However the same link also clearly states it’s the IAT that the ECM (AKA the PCM) which affects engine management and that the AAT has nothing to do with engine management, which uses the IAT.

I also proved the P0074 should display as “Ambient Air Temperature Sensor Intermittent” and not “Ambient Air Temperature Sensor Cylinder Bank 2“. The P0074 is a generic OBD2 fault, not a Ferrari specific fault code, so it cannot have another text description or functional purpose. Ferrari cannot redefine a generic OBD2 fault. If all manufacturers were allowed to do that OBD2 codes would not be consistent and there would be chaos.

The simple explanation is that the OP’s OBD2 scanner has a typo in the lookup table it uses to display the P0074. Have you read over the information I posted and thought your comment over carefully before posting? You have been wrong before.

 

I am make mistakes all the time, and am wrong on a bunch of things (just ask my wife), as I am only human. But you are wrong in this case.

What is a PCM or the ECM? Ferrari does not use those acronyms for any control unit in the car. The engine ECU's are know as NCM's. Every Ferrari since the 360 Modena uses the ambient temperature sensor (the nub on the bottom of the left outside mirror) as an input to both the right and left NCM. The NCMs receive this input over a CAN bus that is networked with the other ECU's in the car.
It uses the outside temperature information, as well as the engine temperature information to see if there is a plausibility error with either of the intake air temperature sensors. There are four Ferrari DTC's P0071,P0072,P0073 and P0074 that all relate to improper inputs from the ambient air temperature sensor. P0074 is the DTC that is stored if the sensor is disconnected.

If you looked at any of the lists of Ferrari specific DTC's, You would have seen this. Different manufacturers use the same OBDII fault code for very different faults all the time. The OBDII code for a Ferrari often has a very different description from other manufacturers cars.

Brian Brown
San Francisco Motorsports

 

Sorry but unless there are additional error codes, there is no way an error in the AAT on the driver mirror can identify a problem in Bank 1 or Bank 2.

I suspect the PCM (ECM) uses the AAT to determine if there is a gross error in the IAT or AAT sensor readings. In the case of the IATs, it may be situations where there is a leak in the intake grommet(s) and hot engine compartment air is reaching the MAF or one MAF IAT is reading significantly different from the othe and the AAT reading is then compared. The AAT alone simply cannot tell the difference between the air reaching the 2 cylinder banks. It would be inappropriate and inaccurate.

These are generic OBD2 codes and they cannot be used for flagging vendor specific conditions. Ferrari has its own Ferrari-specific codes and can use those codes to provide additional information. Again, generic OBD2 codes cannot be used for vendor specific purposes or else they are NO LONGER GENERIC.

The link I provided clearly states "...the AAT sensor has nothing to do with engine operations". I have provided you with valid reasons why the PCM uses AAT readings.

Think about it - if the OP put back the AAT and it cleared the error then how can the P0074 error code text description be correct? It was flagging a problem in Bank 2! It wasn't flagging a problem with the AAT. How does putting back the AAT solve a problem in Bank 2? You're wrong.

 

Think whatever you want. Do you actually work on any Ferraris?
Unplug the ambient air temperature sensor/mirror connector and use a Ferrari Diagnostic tool (SD2, SD3, SDX, DEIS, Leonardo, ETC) to see what fault codes are stored in each NCM and then tell me what you find.

 

No and that’s why I still have lots of healthy respect for you and for other experts like yourself.

However, service shops no longer have the means or interest to diagnose car problems beyond what their instruments tell them. Service garages are more like family health clinics, where family doctors can only spend so much time on patients and then send them to specialists for anything beyond routine. It’s like first line support vs second line or factory tech support. BTW, the OP is also not Ferrari trained and I don’t think he has a DEIS.

This is also why non-routine Ferrari car diagnosis involves having Ferrari technicians in Italy connect to those cars remotely or they instruct local technicians to collect and forward specific data to them for deeper diagnosis. There are many things your shop tools cannot diagnose and in this case, I suspect the tool the OP is using has a flaw in its fault code display. If the technician’s tool is faulty and the tech is not used to thinking past what his tools tells him you can imagine how confused things can get.

Industry standards like OBD2 can only exist as industry STANDARDS if they are consistently applied across the car industry, with all car makers. So generic fault codes must remain generic in application or generic diagnostic tools like OBD2 readers would never be practical and costs would be prohibitive because they have to recognize completely different sets of codes for each car maker or car model. Each car maker would charge a huge royalty to provide such information because not doing so would bankrupt their DEIS business and also put many Ferrari trained service shops out of business if it only takes a cheap tool made in China to do what a dealer service can do.

I used to work in research and I also designed and built software that operated industry standard high tech factory equipment and robots so I think and look at unusual problems in a way similar to factory techs for complex modern car problems, because we look at how the systems are designed to work at the low or lower levels and rely very little on high level test equipment.