Here's a breakdown of the codes and potential repair steps. Remember to consult your vehicle's repair manual for specific procedures and torque specifications.
* P136 (and potentially P156): These codes often relate to problems with the ignition system, specifically issues with the ignition coil packs, spark plugs, or wiring. They could indicate a misfire in one or more cylinders.
* Troubleshooting Steps:
* Visually inspect: Check all ignition coil packs for cracks, damage, or loose connections. Inspect spark plug wires for damage or fraying.
* Spark Plug Inspection: Remove and inspect spark plugs. Look for excessive wear, fouling, or damage. Replace if necessary. Use the correct spark plug type and gap specified in your owner's manual.
* Coil Pack Testing: You might need a multimeter to test the coil packs for resistance and proper voltage. A bad coil pack will need replacement.
* Wiring Inspection: Carefully check all wiring related to the ignition system for damage, shorts, or loose connections. Repair or replace as needed.
* P1131: This code indicates a problem with the upstream oxygen sensor (O2 sensor) on Bank 1 (typically the driver's side). It suggests the sensor is not providing a proper signal to the PCM (Powertrain Control Module).
* Troubleshooting Steps:
* Visual Inspection: Inspect the O2 sensor for physical damage, corrosion, or loose connections.
* Sensor Testing: An O2 sensor test can be performed with a multimeter to check for proper voltage output. A faulty sensor needs replacement.
* P1151: This code is similar to P1131 but pertains to the upstream O2 sensor on Bank 2 (typically the passenger's side).
* Troubleshooting Steps: Same as P1131, but focus on the Bank 2 O2 sensor.
Repair Steps (General):
1. Clear the Codes: After performing any repairs, use an OBD-II scanner to clear the trouble codes from the PCM.
2. Road Test: Drive the vehicle to see if the codes return.
3. Repeat as Necessary: If codes persist, repeat the diagnostic process, focusing on the remaining potential issues.
Important Considerations:
* Professional Help: If you are not comfortable performing these repairs yourself, take your Expedition to a qualified mechanic. Improper repairs can lead to more significant problems and expensive repairs.
* OBD-II Scanner: An OBD-II scanner is crucial for reading and clearing trouble codes. A higher-end scanner may provide more detailed diagnostic information.
* Safety: Always disconnect the negative battery terminal before working on any electrical components. Be careful when working under the hood and follow proper safety precautions.
* Parts Quality: Use only high-quality replacement parts. Using cheap parts can lead to premature failure and recurring problems.
This information is for guidance only. The specific cause and solution for your Ford Expedition's codes will depend on the unique circumstances of your vehicle. Proper diagnosis is essential for accurate and effective repairs.
