P0343

P0343 means the Bank 1 CMP signal voltage is stuck above the high-threshold limit — the signal is pegged at reference voltage with no pulsing, indicating an open circuit, a sensor with internal open, or a signal wire shorted to a 12V source. The behavior mirrors P0338 on the cam side. Cheapest-first ladder: key on engine off, back-probe signal wire at ECM and verify the wire reads the expected reference voltage (typically 5V); then unplug the sensor and verify the signal wire drops toward 0V — if it stays pegged high, you have a short to power upstream of the sensor. With sensor plugged in, scope during cranking — a healthy Hall CMP should pulse 0-5V cleanly; a stuck-high signal means the sensor's internal switching transistor is open. Inspect the connector pins for backed-out terminals (heat cycling pushes pins out of the housing and breaks contact). Check sensor ground continuity to ECM ground — an open ground at the sensor side will present as a stuck-high signal because the pull-up resistor inside the ECM has nothing to pull against.

Vehicle-specific patterns: Chrysler 3.6 Pentastar sets P0343 when the CMP connector locking tab breaks and the connector backs off slightly under hood vibration — push it on firmly and the code clears for 50,000 miles. Ford 5.4 3V triton CMPs fail open from internal connector pin corrosion behind the connector seal. BMW N54/N55 throws P0343 from heat-soaked Vanos sensors and the connector pigtail degrades simultaneously — replace both. Toyota 2GR-FE (Camry, Avalon, Highlander, Sienna 2007-2017) sees occasional P0343 from a recall-related TSB on early production CMP sensors with internal Hall-IC failures. Estimated repair: $140 to $520.