P0420 on Nissan: How to Diagnose & Fix

The 2004-2015 Titan VK56DE engine is prone to exhaust manifold bolt failure due to thermal cycling. The bolts break or the manifold cracks or warps, causing an exhaust leak that sounds like a ticking noise on cold start. The issue affects both banks but the driver's side (bank 1) is more common. Broken bolts can be extremely difficult to extract.

The 2009-2014 Murano VQ35DE 3.5L V6 engine can consume excessive amounts of oil, sometimes 1 quart every 1,000-2,000 miles. The issue is caused by worn piston rings and valve stem seals. A Nissan dealer can perform an oil consumption test; if the engine fails it while under warranty, Nissan may authorize repairs.

The Murano VQ35DE is prone to premature catalytic converter failure, often between 80,000-120,000 miles. The Bank 1 (firewall side) converter typically fails first. Contributing factors include the engine's tendency toward oil consumption, which poisons the catalyst, and heat soak from the converter's close proximity to the engine. Failed converters trigger emission codes and can cause reduced power and failed emissions tests.

The NV200 is one of the most targeted vehicles for catalytic converter theft due to its higher ground clearance and easily accessible exhaust system. Muffler shops report seeing 2-10 NV200s per week with stolen converters. Thieves can remove the catalytic converters in under two minutes. The NV200 has two catalytic converters, and often both are stolen. Replacement costs are significant and the vehicle cannot pass emissions inspection without them.

The catalytic converter degrades or clogs over time (often accelerated by a rich fuel condition from a failing upstream O2 sensor, MAF sensor, or worn plugs), setting a P0420 catalyst-efficiency check-engine light and causing sluggish acceleration and rattling from a broken internal substrate. Separately, the Rogue's converter is a known theft target on some model years; theft leaves a very loud exhaust and a P0420 code.

The VQ35DE runs close-coupled pre-catalysts in the exhaust manifolds. When the ceramic substrate breaks down — accelerated by an engine already consuming oil, by misfires, or by heat — the fine abrasive debris can be drawn back into a cylinder during valve overlap and at high rpm, where it scores the bore and wrecks the rings. The result is not a converter repair but a rebuilt or replaced engine, and it is the single most consequential thing to check before buying an early Z. It compounds the known VQ35DE oil-consumption problem: burning oil poisons the cats, and dying cats then kill the engine. Owner reports cluster well into six figures of mileage. The 2007-2009 VQ35HR uses a different exhaust manifold/catalyst arrangement and does not carry this reputation.

The revised VQ35DE "Rev-Up" engine (2005-2006 350Z) is notorious for excessive oil consumption, often burning 1 quart every 1,000-2,000 miles. Nissan covered it in technical bulletin NTB07-088 (later revised as NTB07-088d) for 2005 Track and 35th Anniversary manual cars and 2006 manual cars: after an oil-consumption test, the remedy for excessive consumption was replacing the short engine assembly, and some owners report the replacement engine also used oil. The standard VQ35DE (2003-2004) and the later VQ35HR (2007-2009) do not suffer from this issue to the same degree. Nissan acknowledged the problem but did not issue a recall. The Rev-Up engine can be identified by its higher redline (7,000 vs 6,600 RPM).

On many 2.5L QR25DE Altimas, the pre-catalytic converter material can deteriorate and be drawn back into the engine during valve overlap, scoring cylinder walls and accelerating oil consumption. Owners report needing to add oil frequently, loss of compression, rough running, and in severe cases complete engine failure. This issue is widely discussed in owner communities and tied to Nissan service information addressing catalyst and ECM updates on affected 2.5L cars.

The R52 Pathfinder with the VQ35DE (2013-2016) and VQ35DD (2017-2020) engines experiences premature catalytic converter failure, often between 80,000-120,000 miles. The catalytic converters can become clogged or the catalyst substrate breaks down, triggering P0420/P0430 codes. Contributing factors include the CVT issues that can cause rich running conditions, oil consumption, and short trip driving. The Pathfinder uses two catalytic converters (Bank 1 and Bank 2).

A recurring Versa complaint across both the 1.6L HR16DE and the 1.8L MR18DE is oil disappearing with no drips on the driveway and no visible smoke. The two mechanisms owners and mechanics land on are oil-control ring coking — the low-tension rings carbon up in their grooves and stop scraping — and worn valve guides/stem seals letting oil down the intake ports at idle and on overrun. The MR18DE compounds this with a plated aluminum bore rather than iron liners; where the plating is imperfect the bore wears and consumption climbs early. Forum reports span the whole range from a mild 200 ml per 1,500 km on a high-mileage car (arguably normal) to genuinely defective cases burning a quart every 200 miles by 75,000 miles. The real danger is not the oil cost: the Versa has no low-oil-level warning, only a pressure light that comes on far too late, so owners who trust the change interval run the engine dangerously low and destroy bearings or seize the engine.

Owners of sixth-generation Maximas report check-engine code P0420 traced to a failed bank 1 catalytic converter mounted at the exhaust manifold, which they replaced. It affects 2004-2008 Maximas (A34) with the 3.5L VQ35DE V6; the owner reports include a 2006 Maxima.

Owners of second-generation Frontiers with the 4.0L V6 report a check-engine light with P0420 (bank 1) or P0430 (bank 2). These codes mean the engine computer sees the downstream oxygen sensor reading too much like the upstream one, which suggests the converter is not cleaning the exhaust well enough. That reading does not prove the converter itself has failed. In an archived 2005 Frontier discussion, both codes stayed after an idle relearn fixed a separate high-idle problem. A 2008 owner reports P0420 coming back after earlier repairs. On a related Nissan, a 2006 Xterra owner still had both codes after replacing the O2 sensors and one converter. Replies in that thread suggested checking for an exhaust leak or cracked exhaust headers.

The TA60 runs close-coupled converters bolted to the manifolds plus secondary converters downstream. Owners repeatedly report the ceramic substrate in an upstream converter breaking apart, at which point the loose material blows downstream and packs the secondary converter, choking the exhaust. Symptoms progress from a P0420/P0430 efficiency code to a rattle from the exhaust, then to a truck that will not pull, runs hot, and feels like it has lost half its power because it cannot exhale. Because the same codes are also set by lazy oxygen sensors, plenty of owners replace sensors first and are surprised when the codes come back.

The VK56DE V8 in the first-gen Armada is known for cracked exhaust manifolds. The manifolds crack from repeated heating and cooling, causing an exhaust leak that typically sounds like a ticking noise on cold start, usually noticed around 100,000 miles. Nissan added reinforcement to the manifolds around 2007, but that did not eliminate the problem. A large enough leak can also bring on a check engine light.