For most people with an upgraded intercooler of any kind, there are pretty good odds that you have encountered the p011c code. This can also occur with cold air intakes, but today we will be covering it as it relates to intercooler upgrades. It appears, then it will disappear, rinse and repeat. If you follow diagnostic steps, and/or replace both temp sensors, the code can still persist. We figured out why. This write up has a lot of information condensed down to make it easier to understand, and as such some technical details may not be completely accurate, but call it creative license for explaining the issue at hand.

The diagnostic information for the code states two parameters that are checked to trigger the code:

• ECM detects a state that the temperature difference between intake air temperature sensor 1 and 2 remains 20°C (36°F) or less continuously for 5 seconds or more
• ECM detects a state that the difference between the temperature of intake air temperature sensor 2 and its estimated temperature calculated by ECM from intake air temperature 1 and turbocharger boost sensor remains 106°C (191°F) or more continuously for 5 seconds or more.

We have determined that the triggering cause as it relates to upgraded intercoolers is the 1st one.

Before we dive into explaining whats going on and potential solutions, you should understand how the intake/charge air temp system on the Juke works.

Some terminology to get us started:

Intake air Temp: Temp of the air entering the engine via the air box/air filter.
Charge Air Temp: Temp of the air AFTER the air has been compressed and passed through the intercooler.
MAF: Mass Air Flow Sensor, this sensor determines the amount of air that enters the intake, and is used to calculate engine load.
MAP: Manifold Absolute Pressure Senor, or as Nissan calls it for some reason: Boost Sensor. This sensor measures the air pressure in the charge pipe as an absolute value. In other words: at sea level, air pressure is ~14.7PSI. So when the car is making 14 psi of boost, the sensor will see 28.7 psi of absolute pressure.

So, the way the system works is like this: The MAF has a built in temp sensor that detects the intake air temperature. This temperature reading is used to modify the value of the mass calculated by the MAF. Basic physics states: the colder the air is, the more particles are in a set volume of air. I could spend the entire write up explaining how the math in the MAF works: but we are not here for that.

After the air passes through the turbo, it is heated and compressed and pushed through the intercooler. On the other side of the intercooler is the MAP sensor. This sensor also has a built in sensor to measure the air temperature of the charged air, or the compressed air. This temperature is used to calculate fuel trim modification, timing adjustments, and a slew of other air temperature dependent calculations.

From the factory the oem intercooler is designed to keep the charge air temp within a set percent change from the intake air temp. According to the diagnostic aids: the charge air temp in certain closed loop conditions should be >36F but <191F. So in ideal conditions the graph of intake to charge temps should look like this:

As the intake air temps rise, the charge air temps should rise in a similar fashion. The example above shows how this would look. The temps are no less than 36F apart.

Here is where the issue arises from having an upgraded intercooler on the Juke: The OEM intercooler is so less efficient than the aftermarket one, that in a very specific condition, the graph actually looks more like this:

As the intake temps rise, the charge air temps do not, bringing us into the code triggering range.

So: What are theses specific conditions? Long periods of idle, and long stays in traffic.

From what we have figured out: If the vehicle is moving, the system is not monitoring for this code. So, as long as the sensors aren't WAY off (broken), the car will not trigger a code. BUT, if you sit still, the aftermarket intercooler is efficient enough that the charge air temps do not rise wit the intake temps. Why do the intake temps rise? As you sit still, no air circulates through the engine bay and the heat from the engine soaks into the intake. A combination of this makes the intake air temps rise quite a bit. Because of the stock intercooler design, when sitting still, the cooler soaks up slight amounts of heat from the radiator, engine, and AC condenser. This means the charge temps rise almost as much as the intake temps.

Now, with the larger intercooler, the charge air temps do not rise at the same rate. Really, if the cooler is of a good design, the charge air temps should stay pretty close to ambient air. But, because the intake temps rise, you then enter the 36F zone and trigger the code. Now, the code claims the difference needs to be for 5 or more seconds, but that is AFTER the system starts to monitor that in closed loop. So, when sitting in traffic, or idling for prolonged periods of time the conditions for the code are met after X number of seconds or minutes to start monitoring.

So why is the code intermittent? When you start driving you are now operating in a different set of conditions. Not only is the system not in closed loop and monitoring for this specific code has changed its conditions, but the air temps are now different, your intake air temps are not cooler, as air is now circulating through the engine bay. When the conditions of the code are no longer met after X drive cycles, the code will self-clear.

So how do you avoid the code: Outside of not sitting in traffic and idling for long periods of time: not much can be done. Ford had a similar issue with the intercoolers on the Focus RS and implemented a block off plate to reduce the efficiency of the cooler, which is counter productive when you have upgraded the intercooler on the Juke from oem. An alternative, that we have worked on and tested: is using a device that takes the charge air temp, adds X value to the 5V signal read off the charge air sensor then outputs it to the signal wire for the intake temp, thus keeping the sensors in a perfect range of each other at all times. This isn't the best idea for several reasons, thus why we have not sold this as a usable system.

If the code is very persistent due to where you live or drive, downgrading to a “upgraded” side mount intercooler will help, as they are not nearly as efficient as a good front mount. So you get some benefit without the code.

Or if the issue just is related to getting an emissions check done: drive the car on open roads for 100 miles without the code and then get the test done. This is not a suggestion to circumvent local laws, it is just an example as to how to avoid the code being present during the situation in the example.

How did we come to this conclusion: We sell a lot of front mounts. And we get emails about this code from a handful of people each year. Whenever we come across something like this we take down notes about the common issues that are found. In all of these cases: the code is more prevalent in Jukes that are in urban areas or do not do much highway driving: they sit still while running. We have hundreds of data logs from tuning cars on our dyno, and when looking over air temp data, we noticed the trend differences from stock to aftermarket intercoolers.

In the rare instances where we see the code on a stock intercooler car, the issue is usually related to a sensor malfunction, wiring issues, or large air leaks.

Hopefully this helped with any hair pulling this code may have caused you. Feel free to ask questions, we will answer them when we can.