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Technical Description of OBD-II Trouble Code
Circuit for Turbocharger/Supercharger Inlet Pressure Sensor (Downstream of throttle valve)
What does that signify?
This diagnostic trouble code (DTC) is a generic powertrain code that applies to OBD-II equipped vehicles with a turbocharger or supercharger inlet pressure sensor. Various brands of vehicles, including but not limited to Ford, Dodge, Saturn, Nissan, Subaru, and Honda, may have this code. Although it is a generic code, the specific repair steps may vary depending on the make, model, and engine.
This code indicates a malfunction in the Turbo/Supercharger Inlet Pressure Sensor (TCIP) circuit. The turbo/supercharger is responsible for increasing the “volumetric efficiency” (amount of air) in the combustion chamber by creating pressure in the intake system.
In general, turbochargers are exhaust driven and superchargers are belt driven. The inlet of the turbo/supercharger is where they draw filtered air from the air filter. The inlet sensor works with the ECM (Electronic Control Module) or PCM (Powertrain Control Module) to monitor and regulate intake pressure.
The “(Downstream of throttle valve)” indicates the specific inlet sensor that has the malfunction and its location. The pressure sensor may also include a temperature sensor.
This trouble code is closely related to P012B, P012C, P012D, and P012E.
What are some of the symptoms of the code?
Symptoms of a P012A engine code may include:
What are some of the common causes of the code?
Possible causes for this code may include:
What are some of the troubleshooting steps?
Make sure to check for technical service bulletins (TSBs) for your vehicle. For example, there is a known issue with some Ford / F150 EcoBoost engines, and accessing a known fix can save time and money during diagnosis.
Tools
When working with electrical systems, it is recommended to have some basic tools, such as:
Safety Tips
Basic Step #1
Visually inspect the TCIP and its surroundings. Given the nature of these codes, it is highly likely that there is some sort of physical problem causing this issue. Check the harness thoroughly, as the harness for these sensors typically runs along areas where extremely high temperatures are present. To locate which sensor’s circuit is malfunctioning, refer to “Downstream of Throttle valve”. Downstream refers to after the throttle valve or the side closer to the intake manifold. The throttle valve is typically mounted to the intake manifold itself. Once you have located the TCIP, follow the wires coming out of it and inspect for any frayed, chafed, or cut wires that may be causing an issue. Depending on the location of the sensor on your make and model, you may have enough access to the sensor’s connector. If so, you can disconnect it and inspect the pins for corrosion.
NOTE: Green color is an indication of corrosion. Visually inspect all ground straps and look for corroded or loose ground connections. A problem within the general electrical system can cause drivability issues, poor mileage, and other unrelated problems.
Basic Step #2
Depending on the make and model of your vehicle, there may be a fuse box. Fuse boxes can be located just about anywhere in the car, but a few good places to start are under the dash, behind the glove box, under the hood, or under a seat. Locate the fuse and make sure it fits tightly in the slot and is not blown.
Basic Tip #3
Check your filter! Visually inspect the air filter for signs of clogging or dirtiness. A clogged filter may cause a low pressure condition. So, if the air filter is clogged or showing any signs of damage (i.e. water intrusion), it should be replaced. This is a cost-efficient way of ruling out this issue because air filters are often inexpensive and easy to replace.
NOTE: Check if your air filter is cleanable. If so, you may be able to clean it instead of replacing the entire assembly.
Basic Step #4
If everything checks out at this point and you still cannot find a malfunction, verify the circuit itself. This may involve disconnecting the ECM or PCM electrical connector, so make sure your battery is connected. Perform basic electrical tests on the circuit (i.e. check for continuity, check for short to ground, power, etc.). Any open or short indicates a problem that will need to be repaired. Good luck!
Professional Service
While we always recommend seeking mechanical solutions for this issue, if it is not possible, we offer the option to permanently delete this specific DTC. All other codes will continue to function. If you are interested in this option, please upload your ECU file to our portal.
