Fault code P006B is called “MAP – Exhaust Pressure Correlation” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.
Technical description and explained code P006B
Diagnostic code P006B is a generic code defined as a correlation between the manifold absolute pressure sensor (MAP) and the exhaust pressure sensor (EPS). It is set when the PCM detects a discrepancy between the signal voltages of the MAP sensor and the EPS sensor.
The air density in the intake manifold is reflected by the MAP sensor, which sends a voltage signal to the PCM. Diesel-engined vehicles use one or more exhaust pressure sensors to monitor back pressure.
Exhaust back pressure is an indicator of the efficiency of the catalytic converter, particulate filter, and NOx filter. Exhaust back pressure is important for engine performance and emission reduction in modern diesel engines.
Code P006B 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. Which vary by more than the programmed amount over a period of time and under certain circumstances.
In some vehicles, it may take several drive cycles with failure for the MIL to light up.
Symptoms of vehicle malfunctions
The main signal that an error P006B has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.
It can also be warning signs such as:
- The “Check engine” control lamp on the control panel will light up (the code will be stored as a fault).
- Other related fault codes may also be present.
- Decreased engine power.
- High or low fuel mixture condition.
- Black smoke coming out of the exhaust pipe.
- Increased fuel consumption.
- The engine may fail an emissions test.
Error P006B is a serious error, because the correct fuel-air mixture is critical to engine performance and efficiency.
Factors that can cause this error code
The error code P006B can mean that one or more of the following problems have occurred:
- Faulty or damaged manifold absolute pressure sensor (MAP).
- Defective exhaust pressure sensor (EPS).
- Damaged or worn connector of one of the sensors.
- Damaged wiring.
- Insufficient vacuum in engine (vacuum leaks, especially in intake system duct).
- Sometimes faulty PCM module is the cause.
How to fix or reset OBD-2 code P006B
Some suggested steps for troubleshooting and fix the error code P006B:
- Connect an OBD-II scanner to the vehicle’s diagnostic connector and read all stored data and error codes.
- Clear the error codes from the computer memory and test-drive the vehicle to see if code P006B appears again.
- If the code appears again, check all cables and corresponding connectors leading to the MAP and EPS sensors. Make sure they are not broken or frayed. Repair or replace if necessary.
- Inspect and test these sensors. Replace failed ones if necessary.
- Check for vacuum leaks and repair if any are found.
- If faulty PCM is the cause, replace or reprogram it.
Diagnose and repair of problems
Inspect visible damage to sensors, wiring, and connectors. Then start the diagnostic procedure with the scan tool. To determine if error P006B is the only error, if not, it may be worth investigating the other fault codes first.
If no problems are found with damaged or corroded connectors, perform a thorough inspection of all associated wiring. Repair or replace damaged wiring as necessary.
Also check the vacuum lines for damage and leaks. Look at the condition of the air filter, it may be clogged, limiting air flow.
Check the sensors
If the code remains, check the reference voltage on the MAP and EPS sensor connectors. Then check the ground and continuity, especially in the signal wire between the PCM and the sensor connectors, if the resistance is infinite, repair the breakage.
If circuit continuity is normal, check the sensors in operation by connecting the scan tool to the vehicle. If the signal voltage does not change according to the manufacturer’s specifications, replace the faulty sensor.
Often, sensor readings may be stuck at 4.5 volts, regardless of engine operating conditions. This indicates a short between the signal wire and the 5-volt reference wire. If necessary, repair the wiring to remove the short.
If there is no voltage in the signal wire when the sensor connector is disconnected, there is an internal short and the sensor must be replaced.
Also in some cases when error P006B occurs, the PCM may be faulty or in the process of breaking down. This is extremely rare, so before replacing it, it’s best to check everything thoroughly again.
On which vehicles does this problem occur most frequently
Fault code P006B can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:
- Chevrolet
- Dodge
- Ford
- GMC
Fault code P006B can sometimes be found with other errors. The most common are the following: P006A, P006C, P00B8, P0401, P2263.
