P012A Turbo/Supercharger Inlet Pressure Sensor Circuit
OBD-II Trouble Code Technical Description
Turbocharger/Supercharger Inlet Pressure Sensor Circuit (Downstream of throttle valve)
What does that mean?
This diagnostic trouble code (DTC) is a generic powertrain code, which means that it applies to OBD-II equipped vehicles that have a turbocharger or supercharger inlet pressure sensor. Brand of vehicles may include but are not limited to Ford, Dodge, Saturn, Nissan, Subaru, Honda, etc. Although generic, the specific repair steps may vary depending on make/model/engine.
This code indicates some sort of malfunction within the Turbo/Supercharger Inlet Pressure Sensor (TCIP) circuit. The turbo/supercharger are responsible for increasing "volumetric efficiency" (amount of air) within the combustion chamber by creating pressure within the intake system.
Generally speaking Turbochargers are exhaust driven and Superchargers are belt driven. The inlet of the turbo/supercharger is where they get their filtered air from the air filter. The inlet sensor works with the ECM (Electronic Control Module) or PCM (Powertrain Control Module) in order to monitor and regulate intake pressure.
The "(Downstream of throttle valve)" indicates what specific inlet sensor has the malfunction and it's location. The pressure sensor may also incorporate a temperature sensor into it.
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:
Vehicle enters limp mode (Fail safe mode) Engine noises Poor performance Engine misfiring Stalling Poor fuel mileageWhat are some of the common causes of the code?
Causes for this code may be:
Defective Turbo/supercharger inlet pressure sensor Broken or damaged wiring harness Problem within general electrical system ECM issue Pin/connector problem. (i.e. corrosion, overheating etc.) Clogged or damaged air filterWhat are some of the troubleshooting steps?
Be 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 getting access to a known fix can save you time and money during diagnosis.
Tools
Whenever you are working with electrical systems, some of the basic tools that are a good idea to have are:
OBD code reader Multimeter Basic socket set Basic ratchet and wrench sets Basic screwdriver set Rag/shop towels Battery terminal cleaner Service manualSafety Tips
Let engine cool Chalk wheels Wear PPE (Personal protective equipment)Basic Step #1
Visually inspect the TCIP and surroundings. Given the nature of these codes, it is highly likely there is some sort of physical problem causing this issue. That being said, check the harness thoroughly because the harness’ for these sensors typically run along areas where extremely high temperatures are present. In order to locate which sensor’s circuit is malfunctioning refer to "Downstream of Throttle valve". Downstream meaning after the throttle valve or the side closer towards 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/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 sensors connector. If so, you can disconnect it and inspect the pins for corrosion.
NOTE: Green color is a good sign that there is corrosion present. Visually inspect all ground straps and look for corroded or loose ground connections. A problem within the general electrical system can and will cause drivability issues, poor mileage among other unrelated problems.
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