90201-ZV4-010 Honda NUT, SPECIAL (16MM) (Honda Code 3174976).

Removal Procedure
Exhaust Gas Valve (NRS) - Remove (Method 1)
Start By:
If necessary, remove the clean emissions module. Refer to Disassembly and Assembly, "Clean Emissions Module - Remove and Install" for the correct procedure.
Illustration 1 g06515069
Disconnect harness assembly (2).
Cut cable straps (5) and position harness assembly (4) away from bracket (6).
Remove Allen bolts (1) and bracket (6) from exhaust gas valve (3).
Remove exhaust gas valve (3) from exhaust gas valve elbow (8).
Remove O-ring seal (7) (not shown).Exhaust Gas Valve (NRS) - Remove (Method 2)
Sulfuric Acid Burn Hazard may cause serious personal injury or death.The exhaust gas cooler may contain a small amount of sulfuric acid. The use of fuel with sulfur levels greater than 15 ppm may increase the amount of sulfuric acid formed. The sulfuric acid may spill from the cooler during service of the engine. The sulfuric acid will burn the eyes, skin and clothing on contact. Always wear the appropriate personal protective equipment (PPE) that is noted on a material safety data sheet (MSDS) for sulfuric acid. Always follow the directions for first aid that are noted on a material safety data sheet (MSDS) for sulfuric acid.
Keep all parts clean from contaminants.Contaminants may cause rapid wear and shortened component life.
Illustration 2 g02503476
If the Diesel Particulate Filter (DPF) assembly is mounted on the valve mechanism cover, removal of the DPF assembly will be necessary to access the NRS induction mixer. Refer to Disassembly and Assembly, "Diesel Particulate Filter - Remove" for the correct procedure.
If necessary, remove secondary fuel filter base and bracket. Refer to Disassembly and Assembly, "Fuel Filter Base - Remove and Install" for the correct procedure.
If necessary, remove water separator and fuel filter (Primary). Refer to Disassembly and Assembly, "Water Separator and Fuel Filter (Primary) - Remove and Install" for the correct procedure.
Slide locking tab (2) into the unlocked position. Disconnect wiring harness assembly (3) from wiring harness assembly (3) for the wastegate solenoid.
Slide locking tab (5) into the unlocked position. Disconnect wiring harness assembly (4) from outlet pressure sensor (6).
Slide locking tab (11) into the unlocked position. Disconnect wiring harness assembly (10) from inlet pressure sensor (12).
Slide locking tab (15) into the unlocked position. Disconnect harness assembly (13) from temperature sensor (16) for the NRS induction mixer. Cut cable the straps from temperature sensor (16) and position the temperature sensor away from the NRS induction mixer.
Slide locking tab (8) into the unlocked position. Disconnect harness assembly (7) from NRS valve (9).
If necessary, disconnect harness assembly (14) for the glow plug.
Make temporary marks on engine wiring harness to show location of all cable straps that retain the engine wiring harness. Cut all cable straps that retain the engine wiring harness, ensure that all cable straps are removed.
Illustration 3 g02503497
Illustration 4 g02503496
Remove bolt (17) from tube assembly (18).
Loosen hose clamp (21) on hose assembly (20). Remove hose assembly (20) from the connection of inlet connection (26).
Disconnect plastic tube assembly (22) from the valve mechanism cover and the crankcase breather canister. Refer to Disassembly and Assembly, "Crankcase Breather - Remove" for the correct procedure.
Remove bolt from tube assembly (23). Remove banjo bolt (24) and remove sealing washers (25) (not shown).
Remove bolts (27) and nut (31) from inlet connection (26).
Remove inlet connection (26) and spacer (29). Remove gasket (28) (not shown) and gasket (30) (not shown).
Remove bolts (33). Remove the assembly of NRS induction mixer (32) from the cylinder head.
Remove gasket (18) from tube assembly (19).
Remove gasket (34) (not shown) from assembly of NRS induction mixer (32).