DTC P0068 – MAP/MAF & Throttle Position Correlation.

🚗 P0068 – MAP/MAF – Throttle Position Correlation

Meaning

The PCM compares:

Throttle Position Sensor (TPS)

Mass Air Flow Sensor (MAF)

Manifold Absolute Pressure Sensor (MAP)

If the actual airflow (MAF/MAP) does not match the expected airflow based on throttle opening, P0068 sets.

🔧 Common Causes

Air Intake & Vacuum

Intake air leak (between MAF → throttle body)

Loose intake hose / cracked resonator box

Vacuum leak (PCV hose, brake booster hose, manifold gasket)

Sensors

Dirty or faulty MAF sensor

Faulty TPS (dead spots, out-of-range signal)

Faulty MAP sensor giving unstable pressure readings

Contaminated throttle body (causing poor airflow)

Electrical

MAF/MAP/TPS wiring issues (corrosion, loose pins, short to power)

Poor ground for sensors

Battery/charging voltage fluctuations

Mechanical

Sticking throttle plate

Failing electronic throttle actuator

🧪 How to Diagnose (Step-by-Step)

✅ 1. Scan data check

Open live data for:

TPS%

MAF g/s

MAP kPa

RPM

Look for:

TPS increasing but MAF not increasing → airflow issue or dirty MAF.

MAP too high at idle (above 45 kPa) → vacuum leak.

✅ 2. Inspect the air intake

Check air filter condition.

Check MAF sensor housing for cracks.

Make sure the intake pipe is tight and not sucking unmetered air.

✅ 3. Check for vacuum leaks

Use:

Smoke machine (best)

Brake cleaner spray (around manifold hoses)

Look for leaks at:

PCV system

Brake booster hose

Intake manifold gasket

Throttle body gasket

✅ 4. Clean throttle body

A dirty throttle body can cause incorrect airflow.

Steps:

Remove intake pipe

Use throttle cleaner

Clean around the plate edges

Perform throttle body relearn (if required by vehicle)

✅ 5. Inspect & test MAF sensor

Check if sensor wire is dirty → clean with MAF cleaner only

Check live MAF reading at idle:

Petrol: 2–7 g/s

Diesel: 5–12 g/s

Low or unstable reading = weak or contaminated sensor.

✅ 6. Check MAP sensor

At idle:

Petrol: 28–40 kPa
High value = vacuum leak.
Low value = restricted intake or faulty MAP.

✅ 7. Check TPS

Should start 0–20% at closed throttle

Smooth linear increase with pedal

No sudden drops or jumps

Erratic TPS causes correlation failure.

✅ 8. Wiring & connector inspection

Look for:

Green corrosion

Oil contamination near throttle body

Broken harness insulation

Weak ground

Repair as needed.

🛠 Fixes Commonly Solving P0068

Clean throttle body

Clean/replace MAF

Fix vacuum leak

Replace MAP sensor (if readings unstable)

Replace faulty TPS or throttle body assembly

Repair wiring/loose connectors

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