* Faulty Mass Airflow Sensor (MAF): A malfunctioning MAF sensor provides inaccurate readings of the air entering the engine. This leads to a poor air/fuel mixture, potentially causing misfires, power loss, and triggering the check engine light intermittently. The intermittent nature suggests the sensor might be failing gradually or is sensitive to temperature variations.
* Failing Ignition System Components: Issues with spark plugs, ignition wires, the ignition coil, or the distributor (if equipped) can lead to misfires. These misfires can damage the catalytic converter (even a new one) and trigger the check engine light. Intermittent problems would explain the on-and-off nature of the light and power loss.
* Vacuum Leaks: A vacuum leak in the intake system can disrupt the air/fuel mixture. This can cause similar symptoms to a faulty MAF sensor – rough running, power loss, and a check engine light. Leaks are often difficult to pinpoint visually.
* Crank Position Sensor (CKP) or Cam Position Sensor (CMP): These sensors tell the engine's computer the crankshaft and camshaft's position. If either is failing intermittently, the engine timing can be off, leading to power loss and a check engine light.
* Fuel System Issues: While less likely given the new O2 sensors, a problem with the fuel pump, fuel injectors, or fuel pressure regulator could lead to inconsistent fuel delivery. This would impact the engine's performance, causing power loss and triggering the check engine light.
* Wiring or Connector Problems: A loose, corroded, or damaged wire in the engine's electrical system could cause intermittent issues. This could affect various sensors or components, resulting in the symptoms you describe. Pay close attention to the wiring harness near the exhaust manifold as heat can damage it over time.
* Faulty or improperly installed O2 sensors (despite being new): While less likely, it's possible one of the new O2 sensors isn't working correctly or wasn't installed properly. A faulty sensor can still cause issues despite its new status.
What to do:
1. Get a Diagnostic Trouble Code (DTC) Scan: This is the most important step. A code reader will give you specific trouble codes that will greatly narrow down the possibilities. Auto parts stores often offer free code reading services.
2. Check for vacuum leaks: Visually inspect all vacuum lines and hoses for cracks, holes, or loose connections.
3. Inspect the wiring: Carefully examine the wiring harnesses for any damage or corrosion, particularly around the exhaust manifold area.
4. Have a professional mechanic diagnose the issue: If you can't identify the problem yourself after obtaining DTCs, a professional mechanic can perform a thorough diagnosis and repair.
Don't continue to drive the vehicle with the check engine light on and power loss, as this could cause further damage. Get it checked out promptly.
