Vacuum leak at the intake manifold gasket or a cracked intake manifold affecting only the deactivated bank; Faulty or contaminated oxygen sensor on Bank 2 that misreports the air-fuel ratio during deactivation; Leaking fuel injector O-ring or a partially clogged injector on an active cylinder of Bank 2; Exhaust leak upstream of the Bank 2 oxygen sensor allowing outside air to skew the reading; Sticking or leaking cylinder deactivation oil control valve that alters the effective air-fuel ratio on the active cylinders; Low fuel pressure or a weak fuel pump that cannot keep up with demand during the deactivation strategy; Engine mechanical issue such as a leaking intake valve or worn valve guide on the affected bank

DTC codes / P2Exx · Hybrid propulsion / P2E6A

P2E6ASystem Too Lean During Cylinder Deactivation Bank 2

Q: What does code P2E6A mean?

System Too Lean During Cylinder Deactivation Bank 2. P2E6A indicates that the engine computer has detected a lean fuel mixture condition specifically while cylinder deactivation is active on Bank 2 of the engine. The powertrain control module monitors oxygen sensor feedback and fuel trim during the deactivation event, and it sets this code when the exhaust oxygen content indicates too much unburned oxygen, meaning the active cylinders on that bank are receiving insufficient fuel relative to air.

P2E6A indicates that the engine computer has detected a lean fuel mixture condition specifically while cylinder deactivation is active on Bank 2 of the engine. The powertrain control module monitors oxygen sensor feedback and fuel trim during the deactivation event, and it sets this code when the exhaust oxygen content indicates too much unburned oxygen, meaning the active cylinders on that bank are receiving insufficient fuel relative to air.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyProfessional

AreaHybrid propulsion

Symptoms you may notice

Illuminated check engine light, often with no other noticeable symptoms
Slight hesitation or stumble when the engine transitions into or out of cylinder deactivation mode
Reduced fuel economy as the computer adds fuel to compensate for the lean condition
Rough running or vibration that is more pronounced during light-load cruising when deactivation typically occurs
In rare cases, a flashing check engine light if the lean condition becomes severe enough to cause misfires

Common causes, most likely first

Vacuum leak at the intake manifold gasket or a cracked intake manifold affecting only the deactivated bank
Faulty or contaminated oxygen sensor on Bank 2 that misreports the air-fuel ratio during deactivation
Leaking fuel injector O-ring or a partially clogged injector on an active cylinder of Bank 2
Exhaust leak upstream of the Bank 2 oxygen sensor allowing outside air to skew the reading
Sticking or leaking cylinder deactivation oil control valve that alters the effective air-fuel ratio on the active cylinders
Low fuel pressure or a weak fuel pump that cannot keep up with demand during the deactivation strategy
Engine mechanical issue such as a leaking intake valve or worn valve guide on the affected bank

How to diagnose and fix it

Connect a scan tool and verify the code is current, then record freeze-frame data and fuel trim values for both banks during cylinder deactivation
Inspect all intake and vacuum hoses on Bank 2 for cracks, loose clamps, or disconnected lines, and perform a smoke test to confirm no unmetered air is entering
Check the Bank 2 oxygen sensor response with a graphing scan tool, comparing its switching pattern to the Bank 1 sensor during active deactivation
Measure fuel pressure and compare it to the manufacturer's specification, and inspect injector O-rings and injector balance on Bank 2
Perform an exhaust leak test upstream of the Bank 2 oxygen sensor using a smoke machine or by listening for ticking sounds during cold start
Test the cylinder deactivation oil control valve and solenoid for proper operation and inspect the deactivation lifters for sticking or damage
If all external factors check out, perform a compression test and cylinder leak-down test on the affected bank to rule out mechanical valve or piston issues

Cylinder deactivation lean codes often misdiagnosed

A vacuum leak that only affects the deactivated bank can be missed because the leak path may be internal to the intake manifold, such as a cracked runner that only opens when the deactivation flaps move.
The code can be set by a lazy oxygen sensor that responds slowly only during the rapid fuel trim changes of deactivation, even though it passes a standard static oxygen sensor test.
Technicians sometimes replace the catalytic converter on Bank 2 when the lean condition is actually caused by an exhaust leak between the manifold and the converter, which lets oxygen fool the downstream sensor.
Cylinder deactivation systems rely on oil pressure to collapse lifters, so using the wrong oil viscosity or a clogged oil passage can cause a lean condition on the active cylinders without any external leak.
This code does not always mean the engine is dangerously lean; a marginal fuel trim drift during deactivation can set it while the engine still runs acceptably, but ignoring it can lead to converter damage over time.

Can I keep driving with P2E6A?

You can usually continue driving to a repair shop at moderate speeds, but avoid heavy acceleration and towing because a persistent lean condition can overheat the catalytic converter and cause costly damage. If the check engine light begins flashing, pull over safely and stop driving to prevent engine damage.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.