P0133, P0134, and P0301 Diagnostic Guide for 1997 Chrysler Sebring V6

Check for a blown fuse labeled 'O2 Sensor' in the fuse box. If no such fuse exists, inspect the wiring harness to the upstream O2 sensor—potential issues include signal loss or heater circuit failure. A faulty O2 sensor is less likely; instead, it may simply be indicating prolonged rich or lean conditions due to misfire or fuel delivery problems. What specific engine model and configuration does your Sebring have? Good luck—please update if you find anything relevant.

Thanks for the reply! The vehicle is a 1997 Chrysler Sebring with a 2.5L V6 engine. I spoke with the owner today and confirmed that spark plugs and wires have never been replaced—over 97,000 miles on the car. Given this, these components are likely candidates for failure. The Chilton manual specifies a resistance range of 3,000–6,700 ohms per foot for spark plug wires; I plan to verify this with my multimeter. The shop mentioned that accessing the rear three cylinders requires removing the intake manifold—this seems accurate as the plenum covers the wiring. Is there a way to access these without full engine disassembly? On my 1992 Grand Am, rotating the engine forward (by pushing from behind and chocking wheels) allowed easier access. Minivans can be more challenging in this regard. On my 1990 Mustang with EEC-IV, I used a torch to heat the O2 sensor and measured voltage output for basic performance checks. Can a similar method work on the Chrysler Sebring? I suspect that an improperly functioning O2 sensor could delay closed-loop operation due to persistent fuel mixture imbalances. Thanks again for your input—I’ll keep you posted as progress unfolds.

Purchase OEM spark plugs and wires from the dealer. Avoid replacing distributor cap and rotor—careless handling can damage the ignition module, requiring costly distributor replacement. These components are rarely faulty in age but may be failing under high mileage. Since no service has been performed on these parts, they are likely on borrowed time. The intake plenum must be removed to access rear cylinder spark plugs—there is no alternative method due to direct coverage by the plenum. While this task isn’t trivial, it’s manageable for experienced mechanics and shouldn’t be attempted more than once. During disassembly, also inspect wiring connections to both O2 sensors. I’ll check for any Technical Service Bulletins (TSBs) related to P0133/P0134 codes on the 1997 Sebring. These models are sensitive to plug brand and injector cleanliness—consider adding sea foam or a motorvac service prior to tune-up. However, avoid using motorvac with new plugs, as cleaning agents can foul fresh electrodes. Best of luck—please keep me updated.

Thanks again! I believe following the instructions in either the Chilton or Haynes manual should make this repair manageable. Correct? My sister once owned a Chrysler Conquest, and I performed several repairs on it—most notably replacing the oil pump and timing chain assembly, which was labor-intensive due to complex components like adjustable chain guides. After that work, the car ran smoothly. I recall the setup being unusual at the time, and later a turbo bearing replacement was needed. This remains my only extensive experience with a Chrysler vehicle. The process was slow because I was also helping my father-in-law replace an engine in his Chevy 1500. I’m confident she’ll follow your advice to use original Chrysler parts. I’ve already advised her on this point. Similarly, 1990s Ford Escorts were known for being sensitive to spark plug and wire quality—Motorcraft OEM parts are generally recommended for reliable performance.

The Chilton manual should guide you through the process effectively. You’ll likely need a new intake plenum gasket and possibly an EGR tube gasket as well. While you're in there, consider replacing the PCV valve too—it’s a common maintenance item that improves engine health. Good luck—please keep me posted on your progress.