P00BC

What the code means

Code P00BC means the mass air flow sensor (MAF) “A” is reading airflow through the intake tract that is too low. The DME (engine control unit) compares the actual MAF signal against its calculated cylinder-fill model, and when the deviation stays consistently on the low side, it sets the fault.

The intake and air-metering system works like this: the MAF measures the mass of air entering the engine and sends that signal to the DME. The DME uses it to calculate per-cycle cylinder fill, the required fuel quantity, and ignition timing. If the signal reads low, the DME delivers a lean mixture and manages load incorrectly.

Causes of a low MAF signal: a contaminated sensing element, an intake tract leak (unmetered air entering after the MAF), or a failed sensor. The code falls under the intake_maf category and is rated moderate severity.

Symptoms

• The EML light comes on in the instrument cluster.
• Possible engine starting problems.
• Reduced engine power.
• Increased fuel consumption.

Diagnosis and repair

Step 1. Check the MAF sensor

Inspect the mass air flow sensor for contamination. If it's dirty, clean it with a dedicated MAF cleaner.

Step 2. Check the intake tract

Check the intake tract for leaks (unmetered air). Fix any leaks you find.

Step 3. Replace the MAF sensor

If cleaning and sealing the leaks doesn't solve the problem, replace the MAF sensor.