Transmission Cooler Defect Spurs Continued Warning on Nissan Pathfinder, Frontier, and Xterra Models

Consumer complaints about certain 2005 to 2010 Nissan vehicles have multiplied, and repairs can cost thousands of dollars

NCCC is advising consumers to avoid purchasing certain model year 2005 through 2010 Nissan Pathfinder, Frontier, and Xterra vehicles equipped with automatic transmissions. A defect involving the transmission cooler has led to transmission failures, costly repairs, and potential safety hazards. Despite past warranty extensions and litigation, the risk remains, and many owners report failures long after any coverage ends.

Background and Initial Investigation

Concerns about these vehicles date back more than a decade. In 2012, NCCC received numerous complaints from owners alleging sudden transmission failure. The problem was traced to a cracked internal transmission fluid cooler line that runs through the vehicle’s radiator. This defect can allow engine coolant to mix with automatic transmission fluid, creating a contaminated mixture that damages internal transmission components. The resulting breakdown can occur suddenly and leave the vehicle inoperable.

In February 2012, NCCC petitioned the National Highway Traffic Safety Administration to open an investigation. NHTSA’s Office of Defects Investigation began its review in June of that year. At the time, there were 512 official owner complaints, but over the years the number has risen dramatically. Many of these vehicles are now on their second or third owners, which increases the risk that the current driver is unaware of the defect history.

Warranty Extensions and Lawsuit Settlement

Nissan first responded in 2007 by extending the warranty on the transmission oil cooler and radiator assembly from 3 years or 36,000 miles to 8 years or 80,000 miles. Following a class action lawsuit filed in 2010, which alleged that Nissan concealed the defect, the automaker agreed to a settlement that extended partial coverage for up to 10 years or 100,000 miles. Even with this coverage, many owners still faced deductibles as high as $3,000 for repairs, and the coverage did not reimburse everyone who experienced the failure.

Failures Beyond Warranty Periods

One of the ongoing challenges for consumers is that the defect often appears after warranty coverage ends. Transmission failure from coolant contamination can occur gradually, without obvious early warning signs, or suddenly during operation. For used vehicle buyers, there is often no indication at the time of purchase that the radiator and transmission cooler are at risk of failure. NCCC continues to receive reports from drivers facing repair bills ranging from several hundred to several thousand dollars, depending on the parts used and whether labor was performed at a dealership or by an independent mechanic.

Current Advisory

NCCC recommends avoiding purchase of 2005 to 2010 Nissan Pathfinder, Frontier, and Xterra models with automatic transmissions unless there is documentation that the radiator and transmission cooler assembly have been replaced with updated parts or the system has been bypassed entirely using an external transmission cooler. Buyers should request repair records before committing to a purchase. Without proof of repair, the risk of failure remains high.

Aftermarket Repair Options

For current owners, preventive repair is possible. Many mechanics recommend replacing the original radiator and cooler assembly with a new aftermarket part that is not prone to the same failure. Some vehicle owners have opted for a bypass modification, which reroutes the transmission fluid through a separate cooler and eliminates the risk of cross-contamination entirely. Costs vary significantly, from about $80 for do-it-yourself bypass kits to $700 or more for complete radiator replacements at professional repair shops. Using a new part is critical; used or reconditioned radiators can suffer from the same defect as the originals.

Monitoring and Early Detection

If you already own one of these vehicles and have not performed the preventive repair, regular inspection is essential. Check the transmission fluid frequently. In most of these models, the fluid should be a consistent red color, although older fluid may appear darker or brown. If the fluid becomes pink, milky, or streaked with white, it may indicate coolant contamination. This condition is often described as resembling a strawberry milkshake and is a clear warning to stop driving immediately and arrange for a tow to prevent further damage.

Engine coolant should also be checked regularly. Coolant that appears brown, milky, or contains a slimy residue may be contaminated with transmission fluid. Always check coolant only when the engine is cold to avoid injury. Any signs of cross-contamination should prompt immediate mechanical inspection.

Investigation Closure and Current Status

NHTSA has since closed its formal investigation into the issue without ordering a recall. This means that the agency did not require Nissan to replace the affected components in all vehicles. The time limits for joining the earlier class action settlement have also expired. While some owners have pursued claims in small claims court or through private legal action, results vary and depend heavily on documentation of the defect and repair history.

Legal and Consumer Options in North Carolina

In North Carolina, consumers can consult the NC Attorney General’s Office or NCCC for guidance on used vehicle purchases and defect disclosures. While state law does not guarantee free repairs in this situation, it does allow consumers to pursue claims if they can show that a seller knowingly withheld information about a known defect. The North Carolina Lemon Law does not apply to used vehicles outside the original warranty period, but buyers can still rely on general consumer protection statutes for misrepresentation.

Buying Used Vehicles with Known Defect Histories

When shopping for a used Pathfinder, Frontier, or Xterra from the 2005 to 2010 model years, request a vehicle history report and ask specifically about radiator and transmission repairs. Independent inspections before purchase can help identify signs of past coolant or transmission fluid contamination. If the seller cannot provide proof of preventive repair or bypass installation, consider the cost of having it done immediately as part of your decision.

Continuing Risks

Even with replacement parts, some consumers have reported recurrence of the problem, suggesting that certain replacement radiators may still be vulnerable. The safest long-term fix is complete bypass of the internal transmission cooler. While this approach requires installation of an external cooler and may slightly alter warm-up times in cold weather, it eliminates the defect pathway entirely.

Steps for Current Owners

• Inspect both transmission fluid and coolant regularly for signs of contamination.
• Consider preventive repair or bypass before symptoms appear, especially if your vehicle still has the original radiator.
• Keep all repair records, as they may be useful for future sale or legal action.
• Inform potential buyers of the vehicle’s history to avoid legal disputes.
• Explore reputable aftermarket parts suppliers rather than relying solely on OEM parts if those have a history of repeat failure.

Why the Advisory Remains Relevant in 2025

Although these vehicles are now at least fifteen years old, many remain in use, and some are still entering the used market. For buyers on a budget, they can appear to be a bargain, but the potential cost of an unexpected transmission failure can outweigh the savings. Transmission replacement can easily cost $4,000 or more if both the transmission and radiator must be replaced. Preventive action or avoiding purchase altogether remains the most effective strategy to avoid this expense.

Summary

The transmission cooler defect affecting certain 2005 through 2010 Nissan Pathfinder, Frontier, and Xterra vehicles continues to be a risk for owners and buyers. With no recall in place and expired settlement coverage, prevention is key. For current owners, this means regular monitoring and, ideally, replacing or bypassing the defective cooler. For buyers, it means avoiding these models unless there is proof that the problem has been addressed. NCCC’s recommendation stands: avoid purchasing these vehicles with automatic transmissions unless you have clear evidence of corrective work, and if you own one, take preventive measures before a failure leaves you stranded with a costly repair.