Lexus ES 300h PCV or crankcase-ventilation fault: symptoms and diagnosis This Lexus ES guide is based on 7 documented technical cases, including 5 confirmed successful repair outcomes. It summarizes the captured evidence without assuming every vehicle with a similar symptom has the same cause. Documented applicability includes 2013–2018.
What Drivers or Technicians Reported
Documented complaints included: Vehicle intermittently stalled with MIL on.; Auto-up stopped after replacement of the driver master window switch.; Passenger daytime running light stayed on continuously.; Driver door would not lock or unlock from fob or door switch.; C2126 remained after one TPMS transmitter was replaced and its ID registered.; Washer-fluid-level warning remained on after the level switch was replaced and even when disconnected..
Fault Codes Seen in Supporting Cases
Codes included P0171, P0A0F, C2126. A code is a diagnostic clue, not automatic proof that a specific part failed.
Causes Confirmed in Documented Cases
Disconnected PCV hose causing unmetered-air/vacuum leak. Power-window initialization had not been completed after switch replacement. Failed daytime-headlight relay. Failed driver-door lock actuator. Washer-fluid-level-switch connector installed in the wrong orientation.
What the Diagnostic Process Found
0.38 g/s against stated 0.23-0.43 specification Good in both directions Less than 1 ohm low and 5.7 MOhm high
Repairs That Corrected Documented Cases
Reconnect PCV hose and reset KAM. Perform power-window initialization Replace daytime-headlight relay 82720-33351. Replace driver-door lock actuator. Reconnect switch in correct connector orientation
Repairs or Attempts That Did Not Solve the Original Problem
Replace one TPMS transmitter — unsuccessful Register transmitter ID — unsuccessful
Replace washer-fluid-level switch — unsuccessful Replace batteries in both key fobs — unsuccessful
Lexus ES Diagnosis in Hickory, NC
Mich's Foreign Cars has served Hickory and the surrounding Western North Carolina area since 1983. We specialize in European and foreign vehicles and use professional diagnostic equipment to identify the cause before recommending repairs. If your Lexus ES is showing this symptom or fault pattern, call Mich's Foreign Cars at 828-324-6012 to schedule diagnosis.