P0430 and your Nevada smog check

If your truck, SUV or larger sedan has a six or eight cylinder engine in a V, it has two exhaust sides and often two converters. P0430 is about the second one. The smog consequences are the same as for any lit lamp, but a few details, starting with which side of the engine is bank 2, are worth knowing before you talk to anyone about repairs.

At a glance

• SAE J2012 defines P0430 as catalyst system efficiency below threshold (bank 2).
• Only engines with two cylinder banks, such as most V6 and V8 engines, can set it.
• A lit lamp fails a 1996 or newer light-duty vehicle in Nevada; clearing the code earns a not ready rejection instead.
• Converters are among the parts the federal emissions warranty can cover, up to 8 years or 80,000 miles on some components.

Bank 2, explained

SAE J2012 is the standard that sets the meaning of generic OBD II codes, and for P0430 its words are: Catalyst system efficiency below threshold (bank 2). Bank 1 is whichever side of the engine holds cylinder 1. Bank 2 is the opposite side. The engine computer watches each side's converter separately, using an oxygen sensor ahead of it and one after it.

A healthy converter evens out the oxygen in the exhaust, so the rear sensor's signal stays fairly steady while the front one swings. When the rear signal on bank 2 starts copying the front one, the computer decides that converter is no longer doing enough work and sets P0430. Its twin, P0420, is the same test on bank 1. Seeing both at once tells a repair shop something different from seeing only one.

Why the lamp comes on for a converter

The converter is an emission control part, and OBD II was written to watch emission control parts. When the efficiency check fails, the computer stores the code and lights the lamp, and the DMV notes the lamp stays on until the repair is complete. A car with that lamp lit is, in the DMV's words, likely polluting more than it should even if it drives normally.

At the test lane

Our technician scans the VIN, plugs into the diagnostic port and lets the analyzer read the computer. A lit lamp on a 1996 or newer car or light truck means the result is a fail, and the report goes to the DMV electronically like any other result.

That failed report is useful. It documents why the vehicle failed, opens the waiver path, entitles you to a challenge test at the emissions lab and supports a ten-day movement permit if the registration has run out. What does not work is erasing the code on the way in: the computer's self-checks reset with it, and the DMV says that gets the vehicle rejected as not ready.

What a repair shop usually looks at

We test; a repair shop decides what the car needs, and the DMV recommends a 2G licensed authorized station for emissions repairs. Common causes a repair shop checks include:

• The bank 2 converter itself, worn or damaged.
• The bank 2 oxygen sensors and their wiring.
• Exhaust leaks on that side of the engine.
• Misfires or fuel mixture faults on bank 2 that can overheat a converter.

Ask about coverage before you pay

Federal law covers some expensive emission components for up to 8 years or 80,000 miles, and the DMV advises calling the dealer about emissions warranty coverage or a recall first. Two converters can mean two expensive parts, and a vehicle that is eligible for warranty coverage cannot be granted a waiver, so the dealer call is worth making before the first receipt.

When repairs do not clear the lamp

Fail, repair, retest is the normal path in Washoe County. If the lamp is still lit after repairs, the vehicle may qualify for a waiver: at least $200 in parts and labor at a 2G station for repairs directly related to the initial failure, or at least $200 in related parts bought by the owner within 14 days of the initial test. Money spent before the first failed test does not count. The details are on our waiver page.