Mechanic’s solutions that WORKED – Iamcarhacker (2024)

1999 Mercury Villager 3.3L

• Vehicle Information:
  • 1999 Mercury Villager, 3.3L engine

• Issue + Repair History:
  • MIL on and fuel smell reported by the customer.
  • Found three holes in the gas tank caused by a radio shop installing a CD changer.
  • Initial codes: p0138, p0139 (both related to rear O2).
  • Repaired fuel tank and replaced O2 sensor.
  • Two weeks later, MIL on again and slight fuel smell reported.
  • New codes: p0325 (Knock sensor), p0138 (Bank 1 sensor 2 switching slow), p0139 (Bank 1 sensor 2 switching high).

• Community Suggestions:
  • Replace both rear O2 sensors with OEM parts.
  • Check for a reflash for the problem.
  • Note that the p0325 knock sensor code might not trigger the MIL on older Villager models.
  • Check wiring near the O2 sensor connector for any breaks or corrosion.

• Final Fix:
  • The vehicle was not yet fixed at the time of the last update. The technician planned to replace the O2 sensor again.

1997 Jeep Grand Cherokee Laredo 5.2L

• Vehicle Information:
  • 1997 Jeep Grand Cherokee Laredo, 5.2L engine

• Issue + Repair History:
  • Intermittent MIL lamp, turning on and off every two to three weeks.
  • Code retrieved: p138 (high voltage bank one sensor two/ closed loop fault).
  • No specific repair history mentioned.

• Community Suggestions:
  • Bank 1 sensor 2 is the O2 sensor located in the exhaust on the same side as cylinder #1, positioned after the catalytic converter.
  • Unplug the O2 sensors one at a time to identify which one is which.
  • Possible PCM fault; try wiggling the PCM harness to see if the issue can be duplicated.
  • Check if the rear O2 sensor wire is intermittently coming in contact with the driveshaft.

• Final Fix:
  • Replaced bank one sensor 2 (post-catalytic converter) to address the p138 high voltage code.

2006 Chrysler Pacifica Touring 3.5L

• Vehicle Information:
  • 2006 Chrysler Pacifica Touring, 3.5L engine

• Issue + Repair History:
  • Intermittent MIL lamp turning on and off.
  • Codes retrieved: po135 (02 heater performance) and po138 (o2 voltage high).
  • Previous repairs include replacing O2 sensors and the ECM, and checking the wiring.
  • Noted that scanner parameters indicated “not sync,” leading to suspicion about timing belt synchronization.

• Community Suggestions:
  • Check wiring closely and voltage going to O2 sensor.
  • Ensure O2 heater fuse in the underhood fuse box is intact.
  • Use Original Equipment (OE) sensors as Chrysler vehicles typically require OE sensors.
  • Check O2 heater grounds and measure the pulsed 12 volts from the PCM to the O2 sensor heaters.
  • Consider the possibility of the timing being out of sync, although this usually results in a specific DTC or poor running condition.
  • Ensure the correct bank is being addressed; Bank 1 is on the firewall side, Bank 2 is on the front.
  • Check the oxygen sensor heater grounds and the pulsed 12 volts from the PCM to the O2 sensor heaters.

• Final Fix:
  • The issue was found in the harness PCM.

1999 Honda Odyssey LX 3.5L

• Vehicle Information:
  • 1999 Honda Odyssey LX, 3.5L engine

• Issue + Repair History:
  • Vehicle displayed code P0420 (catalyst efficiency low).
  • After clearing the code, emissions were checked. NOX was at 1400 ppm during power braking but below 20 ppm at idle.
  • After driving 10 miles, code P0138 (O2 signal high, bank 1, sensor 2) appeared.
  • Secondary O2 sensor was monitored but showed no issues.
  • Previous repairs: remanufactured catalytic converter installed, both oxygen sensors replaced, EGR valve replaced, and EGR ports cleaned.

• Community Suggestions:
  • Avoid using remanufactured catalytic converters; use Original Equipment (OE) instead.
  • Check the O2 sensor heater fuse and the O2 sensor grounds.
  • Ensure the use of Honda-specific parts, especially for the EGR valve.
  • The after-cat O2 sensor should show a flat line in closed loop; if it’s fluctuating, it might indicate a problem.
  • Consider replacing the O2 sensor if it fails after running for a while.
  • Check if the back O2 is switching between 0.2-0.8 volts in closed loop; if it is, the catalytic converter might need replacement.

• Final Fix:
  • The catalytic converter was replaced again, and the issue was resolved.

2011 Lexus ES350 3.5L

• Vehicle Information:
  • 2011 Lexus ES350, 3.5L engine

• Issue + Repair History:
  • Vehicle displayed code P0138 (Oxygen sensor circuit high voltage, Bank 1 Sensor 2).
  • Sensor was replaced twice using Denso and NGK brands.
  • Bank 1 Sensor 2 showed a voltage 120+ MV higher than Bank 2 Sensor 2.
  • B1S2 impedance was 300 Ohms higher than B2S2.
  • Sensors were swapped, leading to B2S2 showing higher voltage by 120 MV.
  • Suspected a leaking injector initially, but later identified as a circuit issue.
  • Wiring from both rear sensors was load tested and found to be good for 11 amps.
  • ECM was suspected to be the issue.
  • Previous repairs: None mentioned, as it was the vehicle’s first visit.

• Community Suggestions:
  • B1S1 (Bank 1 Sensor 1) might be the cause of the P0138 code. Consider replacing both sensors on Bank 1.
  • Check the O2 sensor heater fuse and the O2 sensor grounds.
  • Ensure the use of Original Equipment (OE) sensors.
  • The rear O2 sensor should not influence fuel mixture. Check the wiring, especially near the exhaust pipe.
  • Consider checking the earth system.
  • Check the A/F Ratio Sensor B1S1 and perform an active test for “A/F Control.”
  • Refer to TSB L-SB-0109-09 for diagnostic tips related to the P0138 code.

• Final Fix:
  • Replaced the B1S1 (Bank 1 Sensor 1) which led to a decrease in fuel trim values to 7% and B1S2 voltage dropped to .7 volts.
  • After road testing for 7 miles, all readiness monitors passed except for the evap system.

Best OBD-II Scanners