Error code P0068 is a generic diagnostic trouble code signaling an engine management problem. This error occurs when there is a difference in readings between the air entering the intake manifold and the throttle position sensor. Thus, this error can also be referred to as the Manifold Absolute Pressure sensor/Mass Air Flow Throttle position correlation. Being a generic code, this error code applies to all vehicle models and makes manufacturers from 1996.
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P0068 Code Definition
- P0068 Generic: Manifold absolute pressure (MAP) sensor/mass airflow (MAF) sensor/throttle position correlation
- P0068 Dodge: Manifold pressure /throttle position correlation
What Does P0068 Mean?
There are three sensors involved in this error code. The sensors are the Throttle Position sensor, the Mass Airflow (MAF) Sensor and the Manifold Air Pressure (MAP) Sensor. These three sensors send information to the Powertrain Control Module. The PCM uses readings from these sensors to determine the fuel to air ratio. When the PCM detects a big variation between the input voltage from the throttle position sensor and the Mass Airflow sensor, code P0068 appears.
The MAF and MAP sensors measure the amount of air coming in through the intake manifold. The throttle position sensor is used by the PCM to detect how open the butterfly valve is, thus regulating the air coming in from the intake manifold.
What Are The Symptoms Of The P0068 Code?
- Check engine light turning on (Service engine soon in some models)
- Drivability issues
- Engine hesitation while accelerating
- Reduced engine performance and reduced fuel efficiency
- Rough Idling
- Loss of power
What Are The Causes Of P0068?
There are several possible causes of P00068 code:
- Any of the three sensors (TPS, MAF MAP) might be damaged
- Vacuum leaks due to damaged vacuum lines
- Leaks in the intake manifold
- Obstructed airflow
- Damaged electrical connectors
- Dry/clogged air cleaner
- Faulty PCM
How Serious Is P0068 Code?
The P0068 code can be categorized as a severe issue. You should not drive with this code as it can be a safety concern. You will experience extreme difficulties, such as loss of power. Rough running will be a major concern. Unresolved, this error code might lead to further engine damage. This code might lead to a lower fuel economy thus costing you more. It is highly advisable to have this code checked and fixed as soon as possible.
How To Diagnose And Fix The Code P0068
Tools you’ll need
- OBD2 scanner
- digital voltmeter/ohmmeter (DVOM)
- service manual for your vehicle
How To Diagnose The Code P0068
Using the OBD2 scan tool, read the error code. Once you diagnose the P0068 code, attempt to reset the code first. After the reset, a short test drive is advisable to check if the code returns. The code might be cleared after the test drive. If it does not, proceed to the next step of fixing it.
How To Fix The Code P0068
- The first step is to perform a thorough visual inspection. Make sure to have turned off the engine at this point. Check for loose wiring and vacuum leaks around the MAF sensor and intake manifold. Check the intake manifold for any obstruction. If you notice anything at this stage, do the necessary repairs. If it is loose wiring, fix it before proceeding. Unplug and replug wiring connectors around the three sensors. If you have done some repairs, recheck if the code is still present. If still present, proceed to the next step.
- Check the air cleaner element for any clogging and dryness. In some cases, this is the culprit. While here check for any leakages
- The next step is to check all the three sensors for corrosion or any other damage. You should clean them if there is any debris build-up. Using a DVOM, check each sensor for voltage and resistance. Consult the service manual for your specific vehicle make/model for correct values. If any of the three sensors have defective readings, replace it. if all the sensors have the correct values, proceed to the next step
- Check the electrical connections from the sensors. Here, you’ll need to measure the resistance on the sensor’s circuits using the DVOM. If you find any open circuit, repair it.
- Sometimes the Powertrain Control Moodle is the problem. This is, however, very rare. If all else fails, check PCM and replace it if faulty.
- By this stage, if you have followed the instructions, you will have found out where the problem is and fixed it. Using the OBD 2 scanner, check if the code is cleared. A test drive is advisable to check if it reappears.
Notes: Since this is a generic code, repair procedure may vary slightly depending on the make and model of your vehicle. The causes and symptoms of code P0068 are varied may also cause other codes. Accurate diagnosis is thus important.
Common Mistakes While Diagnosing The Code P0068
One commonly observed mistake is to quickly assume that the sensors are the problem. Proceeding to replace the three sensors is expensive and might not solve the problem. You should always check for other common causes first before checking on the sensors. To confirm the sensor is the problem, test the voltage and resistance by using a DVOM
Due to the nature of the symptoms associated with this code, it is common to mistake with other problems. This happens even to experienced mechanics. It is paramount to first accurately diagnose the fault then repair it.
Tips to Avoid P0068 In The Future
Making sure you apply anti-corrosion treatment in your engine, especially areas around the MAF sensor and the intake manifold. This will prevent vacuum leaks, which is a major cause of P0068.
Replacing the air filter as scheduled will prevent this problem in the future. Dirty air filters can lead to this code.
