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Honda Odyssey 3.5L Engine Mount Replacement and EGR Code Notes is a working reference for Odyssey owners, technicians, and buyers comparing replacement parts. It covers two problems that tend to show up on this van: exhaust gas recirculation trouble codes, and worn engine mounts that shake the cabin.

The short version: a Honda Odyssey with the 3.5L J35A engine may set Diagnostic Trouble Codes P0400 and P0404, and both relate to the exhaust gas recirculation system. Before you replace the EGR valve, inspect the EGR passages and intake manifold ports for carbon buildup. Separately, worn engine mounts cause noticeable vibration, especially when the vehicle is in gear or under load.

Know the symptoms first

P0400 and P0404: the EGR system

Both codes relate to the exhaust gas recirculation system on the 3.5L J35A. The service note is blunt about the order of operations: inspect first, replace second. Look inside the EGR passages and the intake manifold ports for carbon buildup before spending money on a new EGR valve.

The reason is simple. If the passages are packed with carbon, the restriction stays put after a valve swap and the code can come right back. Inspection costs you time; a misdiagnosed part costs you the part, the labor, and a second visit.

Mount vibration in gear or under load

Worn engine mounts announce themselves through vibration, and the timing matters: it shows up when the vehicle is in gear or under load. The common failure points on this van are the front mount, the rear mount, and the transmission mount. If the cabin shakes under those exact conditions, mounts belong at the top of your suspect list.

What to verify before ordering

Start with the vehicle year, make, model, engine or drivetrain, and the original equipment number printed on the removed part. Match the connector shape, mounting points, dimensions, and left/right position where applicable. A similar-looking component can still be incompatible, so confirm the seller's fitment notes and compare the original part before installation.

• Record the VIN and exact trim level.
• Compare the OE or interchange number and the connector layout.
• Check whether the part is front/rear, left/right, or a complete set.
• Inspect nearby components that could cause the same symptom.

That last item earns its place on the list. A symptom can come from the component next to the one you blame first — exactly why the EGR passages get checked before the valve. A short inspection beats a wrong order and a return shipment every time.

Engine mount replacement: the safe sequence

The published procedure is short, and every step has a reason behind it. Support the engine safely with a jack and a wood block. Remove the through-bolts. Replace the worn mounts with OEM or high-quality aftermarket units. Torque all fasteners to manufacturer specifications.

Step by step

• Position a jack with a wood block and take the engine's weight before loosening any fastener.
• Remove the through-bolts on the failed mount.
• Fit the replacement — OEM or high-quality aftermarket.
• Torque every fastener to the manufacturer specification in the workshop manual.

Finish the job properly: after the repairs, clear the codes and test the vehicle. If a warning light remains on, scan the relevant diagnostic codes and verify the repair instead of replacing additional parts at random.

Rules that apply to the whole job

Disconnect power when the procedure requires it, and support the vehicle correctly before working under it. Follow the workshop manual for torque values and calibration steps. Clean the mating surfaces, route wiring away from heat and moving parts, and test the repair before the van goes back into service.

Spec and procedure summary

Choosing the right replacement

Prioritize verified compatibility, material quality, warranty coverage, and clear product photos. Keep the original part until the new component has been test-fitted and confirmed — it remains your reference for the connector shape, mounting points, and OE number.

For safety-critical systems such as brakes, steering, sensors, and fuel delivery, use the vehicle-specific specification rather than a universal substitute. The same discipline pays off with mounts: match the generation and engine, not just the model name.

A concrete example: KOEEP carries the Engine Motor Mount for the Honda Odyssey & Acura CL 2001-2003, 3.2L (EM9441 / A4519). That is a different generation from the 3.5L J35A van discussed here — same model name, different part. Match your year and engine before ordering, and when in doubt, send the VIN and OE number for a fitment quote.

Related Odyssey maintenance to consider

Mount work puts you in the engine bay anyway, so it is a sensible moment to look at nearby wear items. For the 2011-2017 generation, KOEEP stocks an Electric Engine Radiator Cooling Fan Kit for the 2011-2012 and 2013-2017 Honda Odyssey and a matching Radiator Cooling Fan Assembly for the 2011, 2012, 2013 and 2014-2017 Odyssey.

A cooling fan will not set P0400 or P0404, but a cracked blade or a noisy motor is worth catching while you are already working in the bay — on your schedule, not during an overheating event.

If the van hauls cargo as well as people, the 2026 guide to the roof rack cross bar and side rail set for the 2011-2017 Honda Odyssey covers load ratings and installation for a luggage carrier upgrade.

More KOEEP resources

• If your van is a 2005 or 2006 model, follow the Honda Odyssey Engine Mount Replacement Guide (2005-2006) for a model-year-specific walkthrough.
• The same mount principles apply on a smaller platform — see the 2007-2008 Honda Fit Motor Mount & Transmission Mount Guide.
• For the full catalog of mounts, cooling parts, and more, browse the Auto & Motorcycle Parts one-stop shop.

Frequently asked questions

Quick answers to what owners ask most about this repair.