Manifold Absolute Pressure/Mass Air Flow - Throttle Position Correlation at Idle
This code indicates that inconsistencies have been detected in manifold absolute pressure and/or mass airflow voltage and throttle position for a period exceeding four-seconds continually. A code has been stored and a malfunction indicator lamp may be illuminated. Some manufacturers require multiple failure cycles in order for a malfunction indicator lamp to be illuminated.
Code Set Parameters
An unacceptable manifold absolute pressure and/or mass airflow voltage reading, for the degree of throttle requested, has been detected for a period exceeding four-seconds continually. This reading is measured against the manufacturer’s reference voltage.
Symptoms include failure to accelerate, decreased fuel efficiency, and possibly a service engine soon light.
Common causes of this code are a disconnected plug at the manifold absolute pressure and/or mass airflow sensor/s, moisture or debris that has contaminated the vane of the manifold absolute pressure and/or mass airflow sensor/s, a faulty manifold absolute pressure and/or mass airflow sensor, a cracked or broken air inlet pipe, clogged air filter element, a defective or misadjusted throttle position sensor, or faulty PCM. PCM failures are rare.
Often expensive manifold absolute pressure and/or mass airflow sensors are replaced when a simple cleaning of the mass airflow sensor “hot wire” could rectify the condition. Corroded wiring and/or connectors have also been reported by technicians.
- Several tools will be instrumental in attempting to successfully diagnose this code
- A suitable OBD-II scanner (or code reader) and a digital volt/ohmmeter will be most helpful in trying to perform a successful diagnosis
Begin your diagnosis by visually inspecting all wiring and connectors
- Look for shorted or burned wiring and replace circuitry and connectors as required
If the system wiring, connectors, and components appear to be in normal working order, connect the scanner to the diagnostic connector and record all stored trouble codes and freeze frame data
- This information can be extremely helpful in diagnosing intermittent conditions that may have contributed to this code being stored
- After the codes are cleared, operate the vehicle to see if the code returns
- If the code fails to immediately return, you may have an intermittent condition
- Intermittent conditions can prove to be quite a challenge to diagnose and in extreme cases may have to be allowed to worsen before a correct diagnosis can be made.
Determine whether there is a malfunction in MAF system circuitry, a problem with unmetered air entering the engine, or a problem with an insufficient air supply to the engine
- Check for a clogged air filter element, broken, pinched, or disconnected air inlet pipe, or a vacuum leak prior to beginning an electrical diagnosis
- If these items are found to be in proper working order, check for power and ground at the MAF sensor, as well as sensor voltage to the PCM
- Visually inspect the vane or hot wire of the MAF itself for signs of foreign dirt or other debris
- This can be removed by carefully using an approved chemical cleaner and a cotton swab, then blowing dry with compressed air