Notes: Although it has a stellar record in terms of vehicle problems, initially the 4th generation (2003 - 2009) 4Runner didn't earn our top "Seal of Awesome" rating because it received poor crash test ratings for rear impacts. However it's proven to have one of the lowest driver death rates out of all vehicles (not just SUVs), so we've bumped it back up to our top award.


really awful
Crashes / Fires:
0 / 0
Injuries / Deaths:
0 / 0
Average Mileage:
0 miles

About These NHTSA Complaints:

This data is from the NHTSA — the US gov't agency tasked with vehicle safety. Complaints are spread across multiple & redundant categories, & are not organized by problem.

So how do you find out what problems are occurring? For this NHTSA complaint data, the only way is to read through the comments below. Any duplicates or errors? It's not us.

2003 Toyota 4Runner fuel system problems

fuel system problem

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2003 Toyota 4Runner Owner Comments

problem #1

Aug 052010


  • miles


My 2003 Toyota had emissions issues in that all four oxygen sensors would fail quickly. It took me two years and lots of money later to determine that the cause of this is because transmission fluid is wicking its way through the transmission solenoid harness all the way to the ECU and once there because of the way the ECU is mounted gets into all of the other wiring harnesses of just about every other sensor. I went to Toyota and the first technician never heard that happening before but another overheard our conversation and said "I bet you have a 4runner" so yeah its happened to others. They wanted nearly $4500 to fix the issue. New engine wiring harness $1500-$2000 and another $1000 for the labor and the rest of the estimate is for other parts not specified. Their solution is to cut the wire below the transmission wiring harness connector then splice and solder but I would have to replace nearly all the critical wiring in that car. I cant give an exact date on when it started going wrong but I can look at the service history on the Toyota owner's website and give you this timeline. 0-89,997 - no, issues with emissions or electrical systems. 89,997mi - 90K service done - transmission fluid change w/flush done at dealer. 98,152mi - car reporting lean codes, dealer replaces maf sensor. 100,117 - car reporting lean codes, dealer replaces O2 sensor and A/F sensor bank 2 position 1 & 2 105,312 - car reporting lean codes, dealer replaces bank 1 position 1 A/F sensor and maf sensor again. Total cost $798.76. There are more but I have character limits. I will say this though that the problem should have been obvious because you can clearly see the fluid when you unplug the O2 sensor from the harness but Toyota was content charging me $500-$700 every 10K miles without actually fixing it. Car still remained functional but ruined fuel economy.

- Cabot, AR, USA

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