2020 Honda Civic

The turbocharger bypass control solenoid valve circuit on my 2020 Civic Si has developed an intermittent open, setting DTC P0035. I diagnosed it myself: the solenoid coil measures 45 ohms and functions when commanded via bi-directional scan tool, and supply voltage is present at the harness connector. However, the control circuit reads approximately 9V in the off state when it should be near ground, and the reading fluctuates when the harness is flexed near the connector — indicating a partial break in the wiring consistent with vibration fatigue. This is a safety concern because the ECM fault cascades to other systems. My scan report shows U0401-68 in the ABS module and U0416-68 in both the EPS and Integrated Driver Assistance modules. The result is that VSA stability control is disabled. I first noticed the problem because warning lights appear during hard cornering — precisely when stability control is most needed. Honda has acknowledged this exact failure mode. Service Bulletin 18-044 (NHTSA ID 10142655), issued June 2018, covers the 2017 Civic Type R for DTC P0035 and states the cause as: heat and the natural frequency of the harness cause the coupler wire to oscillate, producing an open circuit to the turbocharger bypass control solenoid valve. The remedy was a replacement engine wire harness kit. The Si shares the same L15B7 engine family and the same bypass control solenoid circuit, but no campaign covers it. Owner forums document numerous P0035 wiring failures on non-Type-R 1.5T Civics. I am requesting that NHTSA consider whether this defect and its effect on stability control warrants a safety investigation and expansion of the existing remedy to other 1.5T Civic models.

The air conditioning system in my 2020 Honda Civic EX has a refrigerant leak at the evaporator assembly, causing very weak or almost no cooling even when set to the lowest temperature settings. This happens consistently, including in moderate to hot outside temperatures, making the cabin uncomfortably warm during drives as it could get pretty hot in inland southern California. The A/C evaporator assembly is the failed component, and the part remains in the vehicle available for inspection if requested. This issue creates a safety risk because reduced visibility from window fogging in humid or rainy conditions (due to lack of proper dehumidification and cooling) can impair safe driving. In extreme heat, it also increases driver fatigue and distraction from discomfort. The problem was confirmed by a Honda dealership through diagnostic testing, which identified the evaporator leaking refrigerant. They previously repaired a related condenser leak under warranty, but the cooling issue persisted and was later traced to the evaporator. The vehicle has been inspected by the dealership (manufacturer-authorized) on multiple occasions for this A/C concern. No specific warning lamps or messages appeared on the dashboard related to the A/C system. This appears to be part of a broader pattern reported by owners of similar 2016-2021 Honda Civics, where condenser failures (sometimes covered by extended warranty) are followed by evaporator leaks, possibly related to the vehicle's use of R-1234yf refrigerant and system pressures. I recently received partial goodwill assistance from the manufacturer toward repair costs, but the issue highlights a recurring defect in the A/C system that affects cooling reliability. This car is driven by my 20 years old daughter as a commuter car to college and she is really suffering. I feel I am putting her at risk and need to get it fixed ASAP at whatever cost.

Q: What component or system failed or malfunctioned, and is it available for inspection upon request? A: BCM (body mechanical module) became faulty, causing car to turn on ignition by itself. Would be sitting in car with it off and the ignition would turn on causing issues with battery and gas consumption. Also in order to save that until it was figured out what was wrong I had to disconnect the battery causing multiple resets to my electrical system. Yes. Q: How was your safety or the safety of others put at risk? A: Would be sitting in car with it off and the ignition would turn on causing startling and issues with battery and gas consumption. Q: Has the problem been reproduced or confirmed by a dealer or independent service center? A: Confirmed and fixed so far by a small and independent electrical mechanic. Q: Has the vehicle or component been inspected by the manufacturer, police, insurance representatives or others? A: No. Q: Were there any warning lamps, messages or other symptoms of the problem prior to the failure, and when did they first appear? A: No.

The vehicle’s emergency braking system randomly applies the brakes even when the front is not obstructed. Front sensors are kept clear of any debris, dirt, or bugs. I went to Honda of El Cajon in El Cajon, Ca and they could not help me even though the service advisor admitted that another Honda CR-V driver had the same problem the same day. This is a safety concern as my car has applied he brakes while on the freeway and at stop signs at random. Honda has failed to acknowledge the issue.