P006B MAP - Exhaust pressure correlation

OBD-II DTC Datasheet

MAP - Exhaust Gas Pressure Correlation

What does this mean?

This Generic Powertrain Diagnostic Trouble Code (DTC) is commonly applied to many OBD-II vehicles. This may include but is not limited to vehicles from Ford, GMC, Chevrolet, Dodge, etc., but appears to be most common on Ford Powerstroke diesel trucks.

If your OBD-II vehicle has stored the P006B code, it means that the powertrain control module (PCM) has detected a mismatch in the correlated signals between the manifold absolute pressure (MAP) sensor and the exhaust gas pressure (EPS) sensor.

In some vehicles, the MAP sensor may be referred to as a barometric pressure sensor. In my professional experience, exhaust gas pressure sensors are only used in diesel vehicles. If other codes are present related to the MAP sensor or exhaust, diagnose and repair them before attempting to diagnose the P006B code.

The MAP sensor measures the density (pressure) of the air in the intake manifold in kilopascals (kPa) or inches of mercury (Hg). These measurements are received by the PCM as input voltage signals. If the MAP signal is replaced by the atmospheric pressure signal, it is still measured in the same increments. Diesel vehicles use one or more exhaust gas pressure sensors to monitor the exhaust back pressure. Exhaust back pressure is an excellent indicator of catalyst efficiency, DPF and NOx filter efficiency. Exhaust back pressure is also critical to engine performance and emission reduction in modern clean combustion diesel engines.

A P006B code will be stored and the Malfunction Indicator Lamp (MIL) may illuminate if the PCM detects voltage input signals (between the MAP sensor and the exhaust pressure sensor) that differ by more than a programmed degree for a specified period of time. time and under certain circumstances. A reliable source of vehicle information (e.g. AllData DIY) will provide the exact parameters for storing the code as they relate to the vehicle in question. In some vehicles, MIL illumination may require multiple drive cycles with failure.

Example of an MAF sensor:

What is the severity of this DTC?

The two sensors associated with this code are critical to engine performance and efficiency. Therefore, P006B should be classified as serious.

What are some of the symptoms of the code?

Symptoms of a P006B engine code may include:

Abnormally excessive smoke from exhaust gases
Excessive fuel consumption
General lack of engine power
Rich or lean exhaust

What are some of the common causes for the code?

Reasons for this code may include:

Defective exhaust gas pressure sensor
Defective MAP sensor
Open or short circuit in wiring or connectors
PCM or PCM programming error

What are some steps to troubleshoot the P006B?

In diagnosing the P006B code, I would have access to a diagnostic scanner, a digital volt / ohmmeter (DVOM), and a reliable source of vehicle information.

Visually inspect all associated wiring and connectors, paying particular attention to wire harnesses and connectors routed near hot exhaust components and sharp edges associated with exhaust shields. If any damaged or burnt areas are found, repair as necessary.

My next step would be to connect the scanner to the vehicle diagnostic port and retrieve all stored codes and freeze frame data. I like to write this information down because it can help me later in my diagnosis. After that, I would clear the codes and test drive the car to see if the code is cleared.

If the code is cleared immediately, I would use the DVOM to check the reference voltage (usually 5 volts) and ground at the MAP and exhaust pressure sensor connectors. I would simply connect the positive test lead of the DVOM to the reference voltage pin of the sensor connector and the negative test lead to ground, and then turn the ignition switch to the ON position.

If both reference voltage and ground are present, I would reconnect the sensor in question and test its signal circuit with the engine running. Use the air pressure and exhaust back pressure for the voltage chart found in the vehicle information source to determine if the corresponding gauges are showing correctly. Any sensors that do not reflect the correct voltage level (according to MAP and exhaust back pressure in the voltage table) should be considered defective.

If the signal circuits of the MAP sensor and exhaust pressure reflect the correct input voltage level (at the sensor connector), use the DVOM to test the appropriate signal circuit at the PCM connector. If there is an accurate sensor signal at the MAP sensor connector and exhaust pressure sensor connector but not at the PCM connector, suspect an open circuit between the PCM and the sensor in question.

You can check MAP sensor and exhaust pressure sensor with DVOM. A reliable source of vehicle information should provide the required specifications. You can use the DVOM (at Ohm setting) to test the MAP and exhaust pressure sensors when they are disabled. If any of the sensors does not meet the manufacturer's specifications, it is considered defective.

As a last resort, turn off the PCM (and all associated controllers) and check individual system circuits with the DVOM. Follow the diagnostic block diagrams, wiring diagrams, and connector pinouts to test the resistance and / or continuity of an individual circuit.

If you have exhausted all other possibilities, you may suspect a PCM failure or a PCM programming error.

Technical Service Bulletins (TSBs) specific to your vehicle (and stored symptoms and codes) can assist in diagnosis.

Related DTC discussions

Error codes P006B, P0401, P2263 Ford DieselHey! Anyone had these 3 codes on a diesel Ford 6.4? Any ideas where to start? Thanks. :) ...

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