Technical Description of OBD-II Trouble Code
Correlation between Manifold Absolute Pressure and Barometric Pressure
What does that signify?
This generic powertrain/engine diagnostic trouble code is typically applicable to all engines equipped with OBDII, but it appears more frequently in certain Audi, Ford, Mazda, Mitsubishi, Saturn, and VW vehicles.
The Manifold Absolute Pressure (MAP) sensor converts engine vacuum into an electrical signal for the Powertrain Control Module (PCM). The engine may also have a Barometric Pressure (BARO or BP) sensor that converts atmospheric pressure into an electrical signal for the PCM.
The PCM receives these inputs, along with possibly two more inputs: Mass Airflow (MAF) and Throttle Position Sensor (TPS), to determine load and altitude. When the ignition switch is first turned on, the PCM examines the MAP sensor voltage and compares it to the BARO sensor reading. This code is triggered if there is too much variation in these inputs. It also analyzes the voltage signals from the MAP and BARO sensors to determine if they are accurate when the throttle is fully open. This would once again indicate barometric pressure.
This code could be triggered by mechanical or electrical issues. The troubleshooting steps may vary depending on the manufacturer, type of MAP/BP sensor, and wire colors.
Symptoms
The symptoms may include:
Causes
Potential causes of a P0069 trouble code may include:
Possible Solutions
A good starting point is always to check for technical service bulletins (TSB) for your particular vehicle. Your issue may be a known problem with a known solution provided by the manufacturer, which can save you time and money during diagnosis.
Next, locate the MAP sensor on your specific vehicle. This sensor is typically found around the intake manifold and the throttle body. Once located, visually inspect the connectors and wiring. Look for any scraping, rubbing, bare wires, burn spots, or melted plastic. Separate the connectors and carefully examine the terminals (the metal parts) inside the connectors. Check if they appear burned or have a green tint indicating corrosion. If necessary, clean the terminals using electrical contact cleaner and a plastic bristle brush. Allow them to dry and apply electrical grease where the terminals make contact. Inspect the vacuum passage from the intake manifold to the MAP sensor, ensuring that it is free from debris and that full manifold vacuum reaches it (put your finger over the opening; it should suck it closed!).
If you have a scan tool, clear the diagnostic trouble codes from memory and see if this code reappears. If it does not, then the connections were likely the problem.
If the P0069 code does reappear, you will need to test the MAP sensor and its associated circuits. With the Key On Engine Off, locate the MAP sensor PID on your scan tool if available. At sea level, it should read 0″ vacuum, approximately 100 kilopascals, or 29.92 inches of mercury. These readings would indicate atmospheric pressure with the Key On Engine Off. Once you start the engine, you should observe the readings changing depending on the engine’s condition and how much you are pressing on the throttle (around 20 inches of vacuum at idle to 2-5 inches at wide open throttle).
If all previous tests have passed and you continue to receive a P0069 code, it most likely indicates a failed MAP sensor, although a failed PCM cannot be ruled out until the MAP sensor has been replaced. If you are unsure, seek assistance from a trained automotive diagnostician. PCMs must be programmed or calibrated to the vehicle in order to be installed correctly.
