Nissan/Infiniti RE5R05A Transmission Service Guide: Pathfinder, Armada, QX56

The RE5R05A is Nissan’s five-speed automatic used in their larger rear-wheel-drive and four-wheel-drive platforms from roughly 2004 onward: Pathfinder, Armada, Titan, Frontier (V6), Xterra, and on the Infiniti side, the QX56, FX45/50, M45, and G35/G37 in some configurations. It is a heavy-duty unit with reasonable durability when maintained, but it has well-documented failure patterns that show up predictably on high-mileage examples.

This guide covers the service procedure, the two most common mechanical failures, and what to look at on a RE5R05A before assuming it needs a full rebuild.

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Fluid Specification and Service Interval

What Fluid the RE5R05A Takes

Nissan specifies Nissan Matic-S fluid for the RE5R05A on most applications, with some later applications using Matic-J or Matic-K depending on the model year and specific production date. Do not use Dexron or generic multi-vehicle ATF in a RE5R05A. The Nissan Matic fluid series has a specific friction modifier package designed for the clutch materials and band linings in this unit. Substituting Dexron VI will cause shift quality degradation and TCC shudder on most RE5R05A applications.

When in doubt about which Matic fluid variant the specific vehicle requires, check the owner’s manual or the service data for that year and application. The distinction between Matic-S, Matic-J, and Matic-K matters — they are not interchangeable in most applications.

Service Interval

Nissan’s factory service interval on the RE5R05A is 30,000 miles under severe duty conditions. In practice, these units come in with 80,000–120,000 miles on the original fluid. The fluid is dark, the filter is bypassing in some cases, and the unit is already showing early symptoms that a timely service would have prevented. Recommend 30,000-mile drain-and-fill intervals to customers who want the unit to last.

Pan Service Procedure

1. Warm the transmission to operating temperature
2. Remove the drain plug — the RE5R05A has a drain plug on the pan on most applications, which simplifies service
3. Remove the pan and inspect contents
4. Replace the filter — the RE5R05A has an internal filter that should be replaced at each service
5. Clean and reinstall pan with fresh gasket
6. Refill with the correct Nissan Matic fluid to the proper level

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Common Failure 1: Front Pump Wear

What the Front Pump Does

The front pump in any automatic transmission is the hydraulic heart of the unit. It is driven directly by the torque converter hub and runs any time the engine is running. The pump provides all hydraulic pressure for clutch apply, band apply, TCC apply, and lubrication throughout the transmission. When the pump wears, line pressure drops and the entire hydraulic system is compromised.

RE5R05A Front Pump Specific Issues

The RE5R05A front pump is known to develop wear in the pump body bore and the pump gears on high-mileage units, particularly those that have been operated with degraded fluid. The symptoms of pump wear are low line pressure, delayed engagement from a cold start (which improves as the transmission warms up and the fluid viscosity drops), and in severe cases, a whine or moan from the pump when the transmission is cold. The whine typically occurs because worn pump clearances allow air entrainment in the fluid at lower temperatures when viscosity is higher.

Diagnosis

One caution before you condemn the pump: on this unit the pilot valve bores in the valve body produce the same complaint. Sonnax documents that pilot valve "A" feeds the line pressure modulating solenoid and the TCC solenoid, while pilot valve "B" feeds the direct and input clutch, front brake band, low coast brake and high and low/Reverse solenoids, and that wear in those bores causes delayed engagement, erratic shifts, flare upshifts, and delayed or no forward and reverse. Their published test for it is a vacuum check that must hold a minimum of 18 in-Hg at the specified location; the repair is pilot valve kit 63741-13K. A worn pilot valve bore will read as low pressure at the tap and send you into a pump you did not need to touch.

Pressure test at the line pressure port is the correct diagnostic step. Low line pressure that improves with temperature indicates pump wear — at lower temperatures the higher viscosity fluid partially compensates for the worn clearances by providing more sealing effect. As the fluid thins with heat, the worn clearances leak more and the pressure advantage of cold temperature disappears. This pattern is specific to pump wear and helps distinguish it from valve body pressure regulator issues.

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Common Failure 2: Solenoid Block Failure

The RE5R05A Solenoid Layout

The RE5R05A uses a solenoid block (also called a solenoid body) mounted on the valve body. This block contains the shift solenoids, the TCC solenoid, and the line pressure control solenoid. The solenoid block is serviceable as a unit — on most RE5R05A applications, the block can be replaced without removing the entire valve body, although the valve body does need to be accessed from inside the pan.

Failure Modes

Before you condemn a solenoid on resistance alone, know which one you are measuring. Per Sonnax's RE5R05A facts and observations, Infiniti used a low-resistance low coast solenoid of 10-15 ohms until August 2005, and from August 2005 on used the same high-resistance 20-40 ohm solenoid Nissan had always used. Sonnax also notes that the Bosch, Nachi and Mitsubishi solenoids are interchangeable as long as the resistance matches. Measure against the right spec for the build date, not a generic range.

Solenoid block failures on the RE5R05A fall into two categories:

• Electrical failure: Individual solenoid coils fail open or shorted. These generate specific electrical codes (circuit high/low) and can be diagnosed with a resistance check at the solenoid connector pins.
• Hydraulic failure: Solenoid plunger bores wear internally, allowing internal leakage. These generate performance codes (circuit performance, ratio error) rather than electrical codes and require replacement rather than resistance testing to confirm.

Common Codes

Codes P0750 through P0770 series (shift solenoid A through E performance/electrical) are the primary solenoid codes on RE5R05A applications. P0740 and P0743 cover TCC solenoid faults. P0745 covers the line pressure control solenoid. A complete code scan with a scan tool that reads Nissan-specific data will identify which circuit has failed before any disassembly.

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Two Things That Bite on High-Mileage Units

The valve body is not one part number. Sonnax documents three RE5R05A valve body designs and states plainly that they should not be interchanged. The first has two neutral-to-reverse accumulators on the lower body behind the manual valve with an empty bore under the low coast solenoid; the second has the same two accumulators but a reverse brake pressure control valve in that bore; the third has a single large neutral-to-reverse accumulator. Not every valve body has a cooler bypass valve either — when it is absent, the separator plate is closed off above that bore. Match the casting to the unit before you order.

Sealing ring land wear drives harsh 1-2 shifts. ATRA's Gears magazine documented a high-mileage RE5R05A whose top sealing ring land measured 0.018 inch clearance against a new ring, more than three times the expected 0.005 inch. The step wear in the land grooves is often invisible to the naked eye — the article's tip is to photograph the lands with a phone and look at the image. Confirm it on the bench with an air check at a maximum of 50 psi regulated air: direct clutch apply should come in around 50 psi, and the failed unit in that write-up needed 70 psi before it would apply.

Check for water while you are in there. Sonnax reports that roughly half the RE5R05A units they receive show water intrusion from radiator cooler failures. If the radiator has ever been suspect on one of these, assume coolant has been through the transmission and inspect accordingly — Transmission Digest has documented converter shudder appearing after exactly that repair.

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The Transfer Case Connection on 4WD Applications

On RE5R05A applications with four-wheel drive — Pathfinder, Armada, Titan, QX56 — a transfer case sits directly behind the transmission. Before condemning the transmission on a 4WD vehicle with shift or engagement complaints, confirm that the transfer case is functioning correctly. Transfer case issues — particularly the electric shift transfer case on later Pathfinder and Armada applications — produce symptoms that are often misdiagnosed as transmission problems. The symptoms overlap: delayed engagement, slipping under acceleration, unusual noise during shifts. Confirming whether the fault is in the transmission or the transfer case before teardown prevents expensive misdiagnosis.