P2097 Code on a GMC: Post Catalyst Fuel Trim High Limit, Bank 1 (GMC Guide)

P2097 on a GMC is GM's "Post Catalyst Fuel Trim System" code for bank 1. On 2012–2018 GMCs, GM's own tables add "High Limit (Too Lean)": the oxygen sensor behind the catalytic converter keeps seeing a lean exhaust, and the engine computer has added as much fuel as its post-catalyst trim allows. GMC owners have two GM playbooks for this code. PIP4964F covers 2008–2023 Acadia, 2010–2017 Terrain and 2015–2022 Canyon V6s and says the most common cause is the fuel injectors, followed by a tiny exhaust leak at the converter outlet. PIP5534A covers the 2018 Acadia 2.5L and Terrain 2.0L turbo — and ends with a line you rarely see in a service document: some P2097s come from how the vehicle is driven, and "there is no fix available." The twist: from 2019, GM's tables relabel P2097 "Too Rich."

What Does P2097 Mean on a GMC?

The front oxygen sensor runs your GMC's main fuel control. The rear sensor — Bank 1 Sensor 2, after the catalytic converter — feeds a slow correction GM calls the post-catalyst integral offset, which biases the front control so the converter works at its best. Zero means balanced. A rear sensor reading lean pushes the offset positive, adding fuel; one reading rich pushes it negative.

In GM's 2017 table for group 03 — covering the Sierra and Yukon 5.3L and 6.2L, the Sierra 4.3L, the Savana 4.8L, the Canyon, the Acadia and the Terrain — P2097 is "Post Catalyst Fuel Trim System High Limit Bank 1 (Too Lean)." It sets when the average integral offset reaches +90% or more and the average total offset is at or above 0%, averaged over 45 seconds. It is a Type B code, two trips. Like its partner P2096, it runs in cruise and acceleration but not at idle or on deceleration, so it tends to appear on the highway and can take several drives to return after being cleared.

Bank 1 is the driver's side on a Sierra, Yukon or Savana V8 and the 4.3L V6, and the rear (firewall) bank on a transverse Acadia or Terrain 3.6L. On the V6 and V8 GMCs, bank 2's version of this code is P2099. On the four-cylinder Acadia, Terrain and Canyon there is only one bank.

Lean, Rich, and the 2019 Flip

Generic code lists usually call P2097 "too rich," which describes the correction rather than what the rear sensor sees. GM's own wording has changed over time, so here is what the GMC tables we checked actually say:

• 2011 (truck group 07: Sierra, Savana, Yukon XL and Canyon engines): no P2097. We found no post-catalyst fuel trim codes in that file.
• 2012 (truck group 07): "High Limit Bank 1 (Too Lean)" — the system "has been unable to adapt to a lean exhaust gas condition."
• 2014 (group 08: Gen V Sierra and Yukon) and 2015–2018: "High Limit Bank 1 (Too Lean)."
• 2019 (group 03B: Sierra, Yukon, Acadia, Canyon; group 03A: Terrain, Canyon 2.5L; group 03C: Savana and Sierra HD 6.0L) and 2020 (group 03D: Savana, Sierra HD 6.6L): "Post Catalyst Fuel Trim System Too Rich Bank 1," set at the low limit (−97.5% in group 03B). P2096 is labelled "Too Lean" in the same files.

We found no GM document explaining the change, so we simply report it. It matters because GM's P2097 bulletins still describe lean causes — and PIP4964F's model list runs through the 2023 Acadia. The practical rule: on a 2019-or-later GMC, do not assume the direction from the code number. Read freeze-frame fuel trims and the rear oxygen sensor voltage, and follow the service information for your VIN. A rear sensor stuck low with positive trims is a lean problem; one stuck high with negative trims is a rich one, whatever the label says.

Which GMCs Set P2097

GM's tables list P2097 for every gasoline GMC engine group we checked from 2012 on:

• Sierra 1500 4.3L, 4.8L, 5.3L, 6.2L and 2.7L turbo; Sierra HD gas 6.0L and 6.6L
• Yukon and Yukon XL 5.3L and 6.2L
• Savana 4.3L, 4.8L and 6.0L
• Canyon 2.5L and 3.6L (and the 2.9L and 3.7L in the 2012 file)
• Acadia 2.5L and 3.6L, and Terrain 1.5L turbo, 2.0L turbo, 2.4L and 3.6L

The Duramax diesels use a different code set, and the Hummer EV has no catalytic converter.

GM's V6 Playbook: PIP4964F

GM preliminary information PIP4964F (April 2025, superseding PIP4964D and earlier versions) is titled "SES Light With A P2097 Or P2099." Its GMC models are:

• 2008–2023 GMC Acadia with the 3.6L LY7, LLT or LGX
• 2015–2022 GMC Canyon with the 3.6L (listed as LFX and LGZ)
• 2010–2017 GMC Terrain with the 3.0L LF1 or LFW, or the 3.6L LFX

GM describes an SES light "with no drivability concerns" and P2097 or P2099 set. Its sequence:

1. Injectors first. "The most common concerns we have seen has been related to fuel injectors." GM says to run an injector balance or AFIT (active fuel injector) test before going further. The bulletin notes the injector balance test is not available on the 2009 Acadia.
2. Then a small exhaust leak, "usually at the outlet to the engine converter." Air pulled in there causes a false lean reading at the rear sensor. GM's method: apply air at 5 to 8 psi to the rear of the downstream converter (or the tailpipe on single systems), then soap the gasket areas and the O2 boss. Leaks that cause the code make larger bubbles; foam is normal. GM warns: do not apply full shop air, as converter and engine damage can result. If a leak is found, GM suggests filing the pipe's mating surface along with the new gasket.
3. Then the valvetrain. If no leak is found, GM says to look for a mechanical concern such as a sticking valve or a lifter follower off the camshaft, which "may or may not cause a misfire."

Note what GM leaves out: no rear oxygen sensor and no catalytic converter appear anywhere in PIP4964F's repair list.

The 2018 Acadia and Terrain Playbook

PIP5534A (October 2018) covers the 2018 GMC Acadia 2.5L (LCV) and 2018 GMC Terrain 2.0L turbo (LTG), alongside Buick, Cadillac and Chevrolet models with the same engines. GM warns that "there are many things that can cause the P2097 and care must be taken when diagnosing this code," and that skipping the service-information diagnostic, which tests the purge valve and lines, "may lead to misdiagnosis." Then:

1. Disconnect the purge solenoid vacuum source at the intake manifold and block the port.
2. Engine warm, A/C and defroster off, watch long-term fuel trim for five minutes each: idling in Park, foot off the brake; idling in Drive on the brake; and at a steady 50 mph or more without cruise.
3. Back in the bay, hold about 2,000 rpm for two minutes and watch long-term trim.
4. If trim was high and then dropped into the normal range (−13% to +13%) and stayed there, suspect a vacuum leak, a skewed MAF, a modified or damaged airbox, or a non-OEM air filter. Swap in known-good parts.
5. If nothing changes, run AFIT on all injectors. If no individual lean injector is found, GM's instruction is to replace all four.

If long-term trim stayed within −13% to +13% throughout, GM tells the technician to ask about heavy stop-and-go driving and to ride along to see whether the owner is a "digital driver" — one who reaches speed, lifts and coasts down a few mph, then gets back on the throttle, over and over. GM's words: "These two driving habits / styles can induce P2097. There is no fix available when the customer drives in this manner."

Symptoms of P2097

• Check engine light on — often the only symptom (both GM bulletins say "no drivability concerns")
• No change in how the GMC drives, in most cases
• Exhaust ticking or puffing near the manifold or converter joint if a leak is the cause
• P2099 for bank 2 at the same time on a V6 or V8 when injectors or a shared cause are involved
• Lean code P0171 alongside when the engine itself is lean

Causes and How to Confirm Each

How Is P2097 Diagnosed on a GMC?

1. Check the VIN for bulletins — PIP4964F on a V6 Acadia, Terrain or Canyon; PIP5534A on a 2018 Acadia 2.5L or Terrain 2.0T.
2. Fix any oxygen sensor, heater, MAF, EVAP or misfire codes first. A rear heater fault such as P0036 stops this test from being trusted.
3. Read freeze-frame fuel trims and rear O2 voltage. On a 2019-or-later GMC, this is how you confirm which direction the problem runs.
4. Test the purge valve and lines per service information, then block the purge source at the intake for the drive test.
5. Run an injector balance or AFIT test — first on a V6 per PIP4964F; after the intake checks on a four-cylinder per PIP5534A.
6. Pressure-test the exhaust at 5–8 psi and soap the converter outlet joint and O2 boss.
7. Check the intake, air filter, airbox and MAF.
8. Consider the valvetrain if everything else checks out on a V6.

Parts and Cost

GM Documents That Name P2097 on GMCs

Have a dealer check your VIN against current bulletins rather than relying on any article, including this one.

What Other P2097 Pages Get Wrong

• "P2097 means the engine is running rich." On 2012–2018 GMCs, GM's tables say "Too Lean." From 2019 the label reverses — read the data.
• "Replace the catalytic converter." Neither PIP4964F nor PIP5534A does.
• Blasting the exhaust with shop air. GM specifies 5–8 psi and warns that full shop air can damage the converter and engine.
• Ignoring the injectors on a V6. GM calls them the most common cause on Acadia, Terrain and Canyon V6s.
• Assuming every P2097 has a part to replace. GM documents a driving-style P2097 with no fix.

Frequently Asked Questions

Is P2097 serious on a GMC?

Usually not. Both GM bulletins describe a check engine light with "no drivability concerns." But if the cause is a lean injector, a vacuum leak or a valvetrain fault, it is worth fixing before it turns into a misfire.

Does P2097 mean rich or lean on my GMC?

On 2012–2018 GMCs, GM's tables say the rear sensor sees lean ("High Limit, Too Lean"). GM's 2019 and 2020 tables label it "Too Rich." Fuel trims and rear O2 voltage settle it.

Why does my Acadia keep setting P2097 with nothing wrong?

On a V6 Acadia, PIP4964F says to test the injectors first, then look for a small exhaust leak at the converter outlet using 5–8 psi air and soapy water. On a 2018 Acadia 2.5L with normal trims through GM's test drive, PIP5534A says driving style can induce it with no fix.

Can an aftermarket air filter cause P2097?

GM thinks so on the 2018 Acadia 2.5L and Terrain 2.0T. PIP5534A lists a non-OEM air filter and a modified or damaged airbox among the causes.

My Canyon has P2097 and P2099 together. What does that mean?

Both banks are affected, which points at something they share or at injectors on both sides. PIP4964F covers both codes on the 2015–2022 Canyon 3.6L.

Will GM replace my injectors for P2097?

PIP5534A directs replacing all four only after the purge, intake, MAF, airbox and filter checks, and only if no single lean injector is found. Coverage depends on your warranty; ask the dealer.

Is there a Chevrolet version of this guide?

Yes. Our Chevrolet P2097 guide covers the Malibu side of GM's bulletins.