P0420 on Nissan: Campaigns, Sensor Names and What to Check

What makes P0420 different on Nissan?

The code itself works the same way. The engine control module (ECM) compares the sensor in front of the converter with the one behind it and sets P0420 when the converter looks too weak on Bank 1. Our main P0420 guide covers the basics.

The Nissan-specific part is a documented campaign. In February 2022 Nissan issued NTB22-006, a voluntary emission service campaign with ID P1A25, for certain 2013 to 2016 Sentra (B17) vehicles. The campaign applies only to California-specification SULEV Sentras, and it is performed at no charge for parts or labor. The dealer reprograms the ECM if its part number is on Nissan's list, then checks the rear oxygen sensor voltage. P0420 is one of the codes the campaign covers, along with oxygen sensor and post-catalyst fuel trim codes ^[1]. You can read the bulletin on NHTSA's document server, static.nhtsa.gov.

The rear sensor check is the interesting part. Nissan's procedure says that if the rear sensor, HO2S2 (B1), reads less than 0.13 V, the sensor has a short to ground condition and must be diagnosed and repaired. A rear sensor stuck low gives the ECM a false picture of what is leaving the converter, which is why a sensor fault can set a converter code.

Which Nissan vehicles have a P0420 bulletin or campaign?

In the NHTSA-hosted documents we reviewed, these are the Nissan and Infiniti items that mention P0420 or the codes that travel with it. Your VIN decides what applies.

Document	Vehicles	What it covers	Action
NTB22-006, campaign P1A25	Some 2013 to 2016 Sentra SULEV (California spec)	P0420 and O2 sensor codes on the covered list	ECM reprogram if needed, rear O2 voltage check, free
Infiniti ITB13-053a	2011 to 2012 Infiniti QX56	P0420 and/or P0430	ECM reprogram if needed; replace that bank's exhaust manifold, three way catalyst and A/F sensor if confirmed
NTB15-115	2015 Altima with 4-cylinder engine	A/F sensor codes, including post-catalyst fuel trim codes P2096 and P2097	ECM reprogram and A/F sensor replacement

The Infiniti QX56 bulletin comes from Nissan's luxury brand. It shows a design detail worth knowing: on that engine the three way catalyst is replaced together with the exhaust manifold, one bank at a time ^[2]. The 2015 Altima bulletin does not list P0420, but it covers the front A/F sensor and post-catalyst fuel trim codes that often appear around a converter complaint ^[3].

We did not find a broad Nissan P0420 bulletin for popular models such as the Altima, Rogue or Versa. If you drive one of those, the normal P0420 diagnosis is the right path. Not sure of your exact model or engine? Our VIN decoder shows the basics.

Is it safe to drive a Nissan with P0420?

Usually yes, in the short term. P0420 rarely changes how the car runs. Book a check rather than ignoring it, because the light being on hides any new problem, and California's Smog Check will not pass a vehicle with the check engine light on ^[5].

If the light starts flashing, or the engine shakes, pull over and stop driving. A flashing light means a misfire, and unburned fuel can overheat the converter. Our guide to a flashing check engine light explains the next steps.

Tell the shop about anything else you notice, such as a rough idle, hesitation or poor fuel economy. Those point to an engine problem that may be feeding the converter, rather than a converter that simply aged, and they change where a technician starts. A car that drives perfectly with only P0420 stored is the more typical picture.

How do you check P0420 on a Nissan?

Knowing Nissan's names makes the live data easier to read. A generic scanner may show "O2 sensor B1S1" and "B1S2", while Nissan's own tool and bulletins use the names below.

1. Read every code and save the freeze frame. A scanner that shows live data and freeze frame is enough; see how to use an OBD2 scanner. Oxygen sensor codes, A/F sensor codes, or fuel trim codes such as P0171 and P0172 change the picture.
2. Ask a Nissan dealer to run the VIN for open campaigns and ECM software. Nissan's bulletins tell owners not to assume a bulletin applies and to see a dealer to confirm.
3. Watch the rear sensor (HO2S2) on a warm engine. One stuck very low points toward the short to ground fault in NTB22-006. One that switches like the front sensor points toward a weak converter.
4. Check fuel trims and look for exhaust leaks with the engine cold, and fix any misfire before anything else. Identifix lists leaks, injectors, fuel pressure, misfires and outdated software among common P0420 causes ^[4].
5. Have a technician verify the converter before it is replaced. On engines where the converter is part of the exhaust manifold, the job is bigger and should be confirmed first.

Note one campaign detail: NTB22-006 tells dealers to check and repair any engine codes before reprogramming, and says codes stored before the reprogram are not covered by the campaign. Write your codes down before the visit so the conversation starts with facts.

The campaign also shows how Nissan confirms a repair. After the reprogram and sensor check, the procedure has the technician drive a set pattern so the System Readiness Test (SRT) status of the HO2S and CATALYST monitors can complete, and then check for codes again ^[1]. That is the same idea any shop should follow: a repair is only proven once the converter test has run and passed. Expect a few days of normal driving before the monitors finish on their own.

How do Nissan P0420 causes compare with the usual ones?

	Generic P0420	Nissan documented cases
Common cause	Worn converter, sensor or leak	ECM software, rear O2 short to ground
Sensor names in data	B1S1, B1S2	A/F sensor 1, HO2S2 (B1)
Readiness name	Monitors	SRT
First stop	Diagnose the cause	Dealer VIN check for campaign P1A25
Who pays	Owner, unless under warranty	Nissan, for eligible Sentra SULEV campaign work

What does a Nissan P0420 repair cost?

If your Sentra is eligible for campaign P1A25, the reprogram and sensor inspection are free ^[1]. Outside that, federal rules give catalytic converters an 8-year or 80,000-mile warranty period on light-duty vehicles ^[6], so check the in-service date and mileage before paying.

Past those, as of November 2026 Identifix cites RepairPal averages of $454 to $550 for an oxygen sensor replacement and $2,301 to $2,473 for a catalytic converter replacement across vehicles ^[4]. We did not find a Nissan-specific price source. Your cost depends on whether the converter is built into the exhaust manifold, how many converters the engine has and local labor rates.

After a repair, clearing the code does not fix anything. The ECM has to rerun its tests, and inspection stations check readiness (SRT) status. Never consider removing or disabling emissions equipment; tampering is illegal under the Clean Air Act ^[7]. For other codes, use our code lookup.