2018 Honda Civic: misfire or rough idle

Filed Oct 10, 2025 · Engine · OH

The engine gasket failed, leaking coolant into Cylinder 3. This created misfires while the vehicle was driving, leading to unpredictable loss of power while driving. Eventually, the coolant purged unbeknownst to the driver and created overheating conditions while driving which could have led to complete engine failure on the road. This behavior was confirmed and reproduced by an independent shop, WenMac Repair, in Hardin County, Ohio. They replaced the spark plugs and coils, thinking the misfire was not necessarily related to the head gasket. The vehicle was then taken to Honda Development and Manufacturing of America, LLC's official repair center for Honda Associates attached to Honda's Marysville Auto Plant 10/1/25 and diagnosed by a Honda master technician. My fiance and I both directly work for Honda. It is currently having the head gasket replaced at a cost of $2,700.00 plus taxes. The vehicle is still in the shop. The failure was observed on vehicle first around 150,000 miles.

Filed Aug 26, 2025 · Fuel system · WA

P0302 Cylinder 2 Misfire Detected, diagnosis concluded fuel injector is faulty, the rest are to follow the same path. Vehicle hesitation happened during highway traffic driving.

Filed Feb 15, 2025 · Engine · MI

Engine failure while driving down the highway. Was able to safely get off the highway without being able to accelerate. Car was towed to the Honda dealership where all the maintenance has been done. They said the car had a cylinder misfire and would need the engine replaced. It would cost $13,000. This car had already had the A/C, fuel pump and transmission replaced in the five short years I owned it. It was garage stored and had under 50,000 miles. All the maintenance was done through a certified Honda dealership.

Filed Nov 2, 2024 · Fuel system · TX

Engine began misfiring and would deliver inconsistent power. The fuel injector was faulty and leaked gas into the engine oil.

Filed Jul 9, 2024 · Fuel system · NC

Multiple misfires and rich fuel codes. Car losses acceleration at high speeds creating safety issue. Faulty fuel injectors. No current recall. Vehicle goes into limp mode.

Filed Jun 14, 2024 · Engine · CA

Headgasket problem Fuel injector Problem Head bolt problem Engine enters limb mode when cold start due to head gasket leak Misfire on multiple cylinders due to fuel injector failure.

Filed Jun 5, 2024 · Engine, Fuel system · 175,000 miles · MD

The contact owns a 2018 Honda Civic. The contact stated while driving at an undisclosed speed, the vehicle entered LIMP Mode and lost motive power. The contact was able to pull to the shoulder of the roadway, where the vehicle was able to be restarted. After restarting the vehicle, the vehicle returned to normal functionality, but the failure became a regular occurrence. The check engine warning light was illuminated. The vehicle was taken to an independent mechanic, who determined that there was a misfire in cylinder #3. The vehicle was not repaired. After investigating the failure, the contact related the failure to the federal safety agency Campaign Number: 23V858000 (Fuel System, Gasoline). The VIN was included, but parts were not yet available. The manufacturer was notified of the failure but provided no assistance. The failure mileage was 175,000.

Filed Mar 15, 2024 · Fuel system · 116,995 miles · FL

The contact owns a 2018 Honda Civic. The contact received notification of the federal safety agency Campaign Number: 23V858000 (Fuel System, Gasoline) however, the part to do the recall repair was not yet available. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The dealer was contacted and confirmed that the parts were not yet available. The contact stated that while accelerating from a stop light, the RPM decreased to zero causing the engine to misfire and the vehicle to stall on several occasions. The fuel and battery warning lights were illuminated. The vehicle was not repaired. The manufacturer was made aware of the failure and created a case file. The approximate failure mileage was 116,995. Parts distribution disconnect.

Filed Jan 11, 2023 · Fuel system · VA

Fuel injectors are fouled up at 25k miles, and cause misfires. Problem had been noted on other Honda vehicles and recall had been issued for the 6 cylinder cars, but not for Civics or 4 cylinder cars. Check engine light, and emissions system warning.

Filed Mar 28, 2022 · Engine · 80,000 miles · IN

The contact owns a 2018 Honda Civic. The contact stated while driving approximately 20 MPH, several unknown warning lights illuminated and the vehicle started to idle very rough. The contact had taken the vehicle to a local dealer however, the vehicle was not diagnosed. The contact drove the vehicle to an independent mechanic who diagnosed that there was an engine cylinder misfire failure with DTC codes: P0302 and P0303. Additionally, the contact stated that there was a strong smell of gasoline in the cabin of the vehicle. The vehicle was not repaired. The manufacturer had been informed of the failure. The failure mileage was approximately 80,000. Fuel injectors were replaced by owner April 10, 2022. Upon oil change the same day, oil was very dark, despite only having 600 miles use since last changed and there was fuel noted in oil. Pictures were sent to the federal safety agency. Since changing injectors fuel mileage has improved greatly. The car has gone from averaging 37MPG to around 41MPG. Oil changed on 6/27/22, coloration was normal for routing change and did not note fuel in oil. No warning lights or issues with operation since injectors changed. The P0302 & P0303 codes were to be covered as part of a service bulletin relating to oil dilution but both Honda corp & dealership stated that injectors were not covered as part of the service bulletin. Even though the injectors could be directly responsible for the oil dilution issue if not properly functioning and throwing codes associated with the bulletin. Owner incurred the expense of rental car for a week, two lost days of onsite work with employer, and cost to purchase injectors. Will provide receipts.

Filed May 28, 2019 · Engine, Fuel system · 10,015 miles · CO

Accelerating up to 60 MPH car began to jerk violently. Flashing check engine light came on and all control of gas petal was lost until car slowed to under 20 - 25 MPH. Obd2 codes pulled and reported misfiring in cylinder 1. Car not able to be driven under any normal conditions as misfiring has intensified. 2018 honda civic si

Filed Nov 7, 2018 · Electrical · 5,600 miles · SC

The engine wiring harness cover composition is attractive to rodents. Squirrels chewed into the harness leading to loss of acceleration. The entire harness needs replacing due to the soy based wire coating. The failure was first noticed while at speed (approximately 35 MPH in city traffic. Subsequent attempts at starting the vehicle resulted in rough idle and dangerous hesitation when merging. Local dealer advises this is a common issue affecting the uk assembled civic hatch back. Estimate for replacement is $900.00 as this is not covered by honda.