What is the P0068 Code?
The P0068 fault code is a generic powertrain code that indicates an abnormal correlation between the Throttle Position Sensor (TPS) and the Mass Air Flow (MAP/MAF) sensor. This issue, present in most vehicles (1996 and newer), indicates a disparity in the air intake data received by the Powertrain Control Module (PCM), preventing it from properly regulating the air-fuel mixture and ignition timing.
Symptoms of the P0068 Code
- ⚠️ Check Engine Light illuminated
- 🔁 Rough idling or engine misfires
- 📉 Loss of power and difficulty accelerating
- ⛽ Increased fuel consumption
- 🚗 Possible stalling or very rough idle
Possible Causes of the P0068 Fault
- 🔧 Air leak or vacuum leak between the MAF sensor and the intake manifold
- 🧽 Dirty or clogged air filter
- 🔌 Corroded, loose, or damaged electrical connectors
- 📏 Faulty MAF or MAP sensor
- 🚗 Malfunctioning Throttle Position Sensor (TPS)
- 🛢️ Throttle body carbon buildup (carbon deposits)
- 🧩 Intake manifold leak
- 🧹 Obstruction in the air intake duct or MAP sensor hose
Diagnosis and Solutions for the P0068 Code
To diagnose and resolve a P0068 code, follow these methodical steps. Equip yourself with a multimeter, test probe, carburetor cleaner, and intake cleaner.
1. Visual Inspection and Cleaning
- Check and replace the air filter if necessary.
- Inspect the hoses and clamps between the MAF sensor and the throttle body (tightness, cracks).
- Check the condition of the vacuum lines on the manifold.
- Clean the throttle body and carbon deposits using an appropriate product.
2. Checking Connectors and Sensors
- Disconnect and inspect the sensor connectors (MAF, MAP, TPS) for corrosion or damaged pins.
- Use contact cleaner to improve the connection if necessary.
3. Testing the MAF Sensor (Mass Air Flow Sensor)
- Engine off, ignition on. Connect the multimeter to the MAF connector (3 wires: +12V, ground, signal).
- Check for 12V at the power terminal. Absence = fuse or wiring problem.
- Check the ground (should be < 100 mV).
- If power and ground are correct but the problem persists, the MAF sensor is likely faulty.
4. Testing the TPS Sensor (Throttle Position Sensor)
- Ignition on, engine off. Connect the multimeter to the signal wire (often blue) and ground.
- The voltage should be approximately 0.5V at closed throttle and gradually increase to ~5V at wide open throttle. An irregular variation indicates a faulty TPS.
5. Testing the MAP Sensor (Manifold Absolute Pressure Sensor)
- Ignition on, engine off: voltage approximately 5V.
- Engine at idle: voltage between 0.5V and 1.5V (depending on altitude).
- The voltage should react instantly to throttle opening (drop then rise). No reaction = faulty sensor.
6. Searching for Air Leaks
- Start the engine and spray carburetor cleaner around the manifold and gaskets.
- A change in engine RPM indicates a leak. Caution: Handle with care to avoid contact with eyes.
Conclusion
The P0068 code is often related to an air intake or sensor problem. Always start with the simplest checks (leaks, filters, connectors) before replacing expensive sensors. If the problem persists after these checks, consultation with an advanced diagnostic tool (such as Tech II) or a professional is recommended.
💡 Tip: Not sure you can perform these checks yourself? Entrust the diagnosis to a qualified mechanic for an accurate diagnosis and reliable repair.