Faulty or dirty fuel injector on cylinder 8 that cannot deliver a consistent pulse; Wiring or connector issue at the cylinder 8 injector, such as corrosion or a loose pin; Mechanical problem in cylinder 8, such as low compression or a sticking valve, that alters combustion stability; Failed crankshaft position sensor or reluctor wheel damage that prevents accurate speed signal learning; PCM software calibration issue or internal fault in the injector driver circuit; Contaminated fuel or fuel pressure problem affecting only one cylinder's injector performance

DTC codes / P2Bxx · Hybrid propulsion / P2B1E

P2B1ECylinder 8 Injection Pulse Offset Not Learned

Q: What does code P2B1E mean?

Cylinder 8 Injection Pulse Offset Not Learned. P2B1E indicates that the powertrain control module (PCM) has not successfully learned the injection pulse offset for cylinder 8, which is the fuel injector timing correction needed for smooth and efficient combustion. The PCM monitors crankshaft speed fluctuations during fuel injection events and expects to complete a learning routine that adjusts for manufacturing tolerances and wear in the injector and cylinder; when that routine fails to complete or the learned value falls outside the acceptable range, this code is stored.

P2B1E indicates that the powertrain control module (PCM) has not successfully learned the injection pulse offset for cylinder 8, which is the fuel injector timing correction needed for smooth and efficient combustion. The PCM monitors crankshaft speed fluctuations during fuel injection events and expects to complete a learning routine that adjusts for manufacturing tolerances and wear in the injector and cylinder; when that routine fails to complete or the learned value falls outside the acceptable range, this code is stored.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyProfessional

AreaHybrid propulsion

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
A slight rough idle or vibration that may be more pronounced when the engine is cold
Intermittent misfire sensation or hesitation during light acceleration
Reduced fuel economy as the PCM defaults to a less optimal injection strategy
In rare cases, a noticeable loss of power or a stumble under load if the offset error is large

Common causes, most likely first

Faulty or dirty fuel injector on cylinder 8 that cannot deliver a consistent pulse
Wiring or connector issue at the cylinder 8 injector, such as corrosion or a loose pin
Mechanical problem in cylinder 8, such as low compression or a sticking valve, that alters combustion stability
Failed crankshaft position sensor or reluctor wheel damage that prevents accurate speed signal learning
PCM software calibration issue or internal fault in the injector driver circuit
Contaminated fuel or fuel pressure problem affecting only one cylinder's injector performance

How to diagnose and fix it

Connect a scan tool and record all stored and pending codes, then clear the code and perform a relearn drive cycle to see if it returns immediately
Inspect the cylinder 8 injector connector and wiring harness for corrosion, chafing, or loose terminals, and repair as needed
Measure the resistance of the cylinder 8 injector and compare it to the manufacturer's specification to rule out an open or shorted coil
Perform a compression test or cylinder leak-down test on cylinder 8 to check for mechanical faults that would prevent offset learning
Check fuel pressure and inspect the injector for clogging; clean or replace the injector if it is not delivering fuel evenly
Verify crankshaft position sensor signal integrity with an oscilloscope and inspect the reluctor wheel for damage or debris
If all hardware checks pass, reprogram the PCM with the latest calibration or replace it if an internal driver fault is confirmed

Why cylinder 8 offset learning fails

A dirty injector that still flows enough fuel to avoid a misfire code can still fail the offset learning routine because the PCM requires a precise, repeatable pulse response that a partially clogged injector cannot provide.
Technicians often replace the injector without checking the crankshaft position sensor signal, but a slightly erratic speed signal will abort the learning process on any cylinder and set this code for the last cylinder in the sequence.
The code can be set by a weak battery or poor ground connection that causes voltage drops during the learning routine, so always check charging system health before condemning hard parts.
On engines with active fuel management or cylinder deactivation, a fault in the lifter or oil control valve for cylinder 8 can alter combustion stability enough to prevent offset learning without setting a dedicated misfire code.
A P2B1E that returns immediately after a successful relearn often points to a PCM calibration mismatch or a failing injector driver inside the PCM rather than a mechanical engine problem.

Can I keep driving with P2B1E?

You can generally continue driving with P2B1E because the engine will run using default injection values, but avoid heavy acceleration or towing until the fault is repaired. Prolonged driving with an uncorrected offset can lead to increased emissions, reduced fuel economy, and eventual damage to the catalytic converter if the cylinder runs too rich or too lean.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

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