2000 Volkswagen New Beetle P1425, P1117, P1435, P1421, P1473, P0102 - Multiple Fault Codes at 135,000 Miles with Poor Engine Performance
Vehicle: 2000 Volkswagen New Beetle 1.8L Turbo (135,000 miles). Recently experienced multiple diagnostic trouble codes including P1425, P1117, P1435, P1421, P1473, and P0102. The car was left unused in the rain for a week, after which it began running poorly. I have already replaced both oxygen (O2) sensors, the engine temperature sensor, and the fuel pump during the summer. I successfully connected to VAG COM to retrieve live data, but am unsure how to interpret the readings or what steps to take next. The issue appears persistent despite these repairs. Given that multiple codes relate to wiring circuits and short-to-ground faults, there is a strong possibility of damaged wiring harnesses—possibly due to rodent activity. Seeking advice on interpreting these specific fault codes and identifying root causes for the 1.8L Turbo engine performance issues.
P0102 = Mass Air Flow (MAF) or Vacuum Air Flow (VAF) Sensor A Circuit Low Input. Recommend checking and cleaning the MAF sensor, as well as inspecting its wiring and connectors for corrosion or damage. P1115 = O2 Heater Circuit B1, S1 Short to Ground P1117 = O2 Heater Circuit B1, S2 Short to Ground P1198 = O-2 Heater Circuit B1, S2 Electrical Malfunction P1421 = Secondary Air Injection Valve Circuit Short to Ground P1425 = Tank Vent Valve Short to Ground P1435 = Secondary Air Injection System Pump Relay Circuit Short to Ground P1473 = EVAP Emission Control LDP Circuit Open Circuit Note: Several of these codes point to wiring faults. It is highly likely that rodent damage has affected the vehicle's wiring harness(es). A thorough inspection of all relevant harnesses—especially near the engine bay and under the hood—is strongly recommended.