Toyota 4RUNNER misfire problems

Filed Sep 23, 2026 · Engine · TX

Head gasket failure. 2005 toyota 4runner generation are notorious for head gasket failure. Due to the poor manufacturing of the gasket it has been deteriorating and has allowed coolant to leak into the cylinder causing misfires and possibly more damage internally. including permanent mechanical breakdown or a completely ruined engine block. High risk of Hydrolock, Damaged Engine Bearings and Sludge, Severe Overheating, Catalytic Converter Failure. Any of these effects cause by this head gasket failure will be extremely dangerous to happen while driving. The vehicles is being taken to a independent mechanic 09/28/2026 for conformation diagnosis. And possible repairs. The check engine light showed the following code-P0300, P0302, P0304. The only symptom where misfiring and coolant levels depleting. The vehicle has not been inspected by the manufacturer, police nor insurance representative. Noticeable misfiring around the beginning of 2025 has just became more aggressive since 2026

Filed Aug 29, 2019 · Engine, Suspension · 217,500 miles · IN

Tl* the contact owns a 2003 toyota 4runner. When the contact attempted to start the vehicle, it would not start. The contact mentioned that the head gasket needed to be removed and re-installed in order to start the vehicle. Also, while driving various speeds, the rear of the vehicle swayed uncontrollably to the left and right. The vehicle was taken to big o tires (2245 state st, new albany, in 47150, 812‑949‑0736) where it was diagnosed that the passenger side control arm was fractured and the driver's side control arm could fracture at any moment. The vehicle was towed to mccormick motor sports (1041 s 6th st, louisville, ky 40203, (502) 584-1981) where the contact was informed that the head gasket was causing cylinder three to misfire. The vehicle was not repaired. The manufacturer was made aware of the failure. The failure mileage was 217,500.

Filed Dec 13, 2018 · Engine · CA

My vehicle was parked in front of my home and when I went out in the morning to take my children to school my vehicle started misfiring all the checks engine lights were lighted up every warning light on my panel lit up. I had my vehicle towed back to the dealer. Come to find out that all my wiring under the hood had been eaten or chewed up by rats. It cost me $500.00 dollars to have it fixed (taped) less than 6 months later it happened again . And less than 3 months after that it happened again! I read somewhere that your vehicles are known to attract rats and that I'm not the only customer to have had this problem. Is there any way you guys are planning to fix this problem any time soon ? It's becoming very expensive for me .

Filed Dec 7, 2018 · Engine · 155,000 miles · NC

Had a misfire in #6 cylinder at 155k miles. I took it to a dealer and they told me that I had a head gasket starting to go bad that let coolant into that cylinder after I shut the engine off resulting in a rough cold start. The tech specialist gave me some nice information and after research I learned toyota knew about the faulty head gaskets in their vehicles and came out with a new redesigned one, but they never told consumers and refuse to fo anything about it. Now my car is in the shop and quoted at $3200.

Filed Mar 10, 2016 · Driver assistance, Electrical · NC

Loss of coolant with no visible signs of leaking. Replaced so many things and keep getting misfires and vsc lights on constantly. Rough start up for about 30 seconds every time started. Slight over heating if idling ... All points now lead to blown head gasket in which I read more and more and common with 04 v6s.

Filed Dec 27, 2015 · Engine · 145,000 miles · MO

This 2004 toyota 4runner had 145000 miles on it when the check engine light came on, along with vsc and vsc trac lights. Engine ran rough/rumbled for few seconds after each start, then the rumbling would stop. At autozone they diagnosed a p0306 error code. Took it to the dealer who scanned code # 0306 #6 cylinder misfire. Further testing showed coolant seeping under headgasket, and dealer recommended replacing cylinder headgasket. Researching the issue, it looks like it's not an uncommon problem with this particular car at this mileage. What made me file this complaint is that each single one of the owners who posted online mentioned this particular diagnosis code of cylinder #6 mifire. I found itinteresting that everybody has the same exact problem, and not even once it was any other cylinder misfire but # 6. I had the dealer replace the headgasket, which took care of the problem, but since it's a recurring problem, I think toyota should take of this issue.

Filed Oct 14, 2015 · Engine · 135,000 miles · IL

Vehicle engine light and other lights came on, took to dealer and told me code was po306 code was diagnosed stating there is a misfire in cylinder #6 resulting in a head gasket problem of coolant entering the cylinder & it would cost me 3000 to 5000 dollars to fix. Every time I start car in morning the car has a rough shacking start until warmed up, my car has 135000 miles & reviewing online this is a common problem with this engine around or after 120000 miles and that their are hundreds of complaints with the exact same issue I am having. Please can one get help in getting toyota accountable for a problem they surely know about as well as because I am not the first and probably not the last on complaining about this issue & that this is not a normal problem for this engine it is a manufactures defect

Filed Jun 19, 2015 · Engine · 125,000 miles · VA

My 4runner check engine light came on and the vsc trak off lights came on with it. The trouble code indicated #6 cylinder misfire. After checking all the sensors it became obvious that there was a slight loss of coolant. Checked the engine and found that the head gasket for #6 had failed. Looking on line I see that there are hundreds of complaints about similar problems around the 120k miles mark. Isn't toyota required to report these to the federal safety agency and should there be a recall on this? This problem seems very similar to an earlier toyota issue that resulted in a recall. A head gasket should not fail during normal use of a vehicle especially one that is used very lightly and not off road.

Filed Dec 28, 2014 · Engine · CA

Cylinder 6 misfires caused by oil leaking into cylinder 6 combustion chamber around spark plug. The issue is traced back to a head gasket failure on the 2004 4runner v6 engine. Cylinder 6 is the weak point where such failures occur especially at start up and when the engine is cold. There is clearly a design flaw in the 2004 v6 4runner's head gasket which requires many hours of labor to repair and should be covered by toyota.

Filed Sep 16, 2013 · Acceleration, Engine · 89,000 miles · RI

Rough idle at morning start up. Vsc, trac off indicators illuminate. Obd ii code of p0306, misfire cylinder #6. Having to refill engine coolant on a weekly basis. Premature head gasket failure. Toyota super long life engine coolant is slowly leaking into cylinder #6. Rough idle noticeable at morning start up because the fluid builds up to a considerable amount overnight. Estimated cost to fix is $3000.