P230B: Cylinder 2 Air-Fuel Ratio Imbalance Adjustment At Limit During Balance
The ECU continuously trims individual cylinders to equalise air-fuel ratio across the bank using ion-current or per-cylinder lambda feedback. For cylinder 2 the per-cylinder fuel correction has hit its software-side maximum or minimum without restoring balance, indicating the underlying mechanical or fuelling deviation is too large to compensate.
What P230B means
P230B is a generic OBD-II powertrain code in the fuel & air group.
- Check engine light
- Usually on
- Emissions-related
- Yes — can fail inspection
- Limp mode possible
- Not typical
- Drive cycle to clear
- Not required
Get it fixed
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Common causes
- 01Fuel injector for cylinder 2 has drifted in flow rateMost likely
- 02Local intake or vacuum leak at cylinder 2Possible
- 03Reduced compression on cylinder 2Possible
Can I drive with P230B?
Usually yes, for a short time.
The car will often drive normally, but get it diagnosed soon. Left alone it can raise fuel use and emissions and will fail an OBD inspection. If you notice rough running, warning lights flashing, overheating or a burning smell, stop driving.
Why we rate it moderate
- Turns on the check engine light
- Emissions-related: will usually fail an OBD inspection
Severity is our rule-based rating from the code’s flags in OBDex and the system it affects, not an inspection of your car. If the check engine light is flashing, or you notice overheating, low oil pressure, or brake or steering problems, stop driving and get help.
How to diagnose P230B
- 1
Confirm the code and save freeze-frame data
Read the codes with an OBD-II scan tool and note every code, not just P230B. Save the freeze-frame data (speed, load, temperature when the fault set) before clearing anything; it tells you when the fault happens.
- 2
Check for related codes first
Look for P230A, P230C, P230D, P230E. Related codes often share a cause; a circuit or sensor code usually needs fixing before a performance code like this one.
- 3
Check live data
Watch the related sensor and actuator readings in live data (Fuel injector cyl 2, Intake manifold, Cylinder compression) and compare them with expected values in the service information for your vehicle.
- 4
Test the likely causes in order
Start with the most likely cause and work down: Fuel injector for cylinder 2 has drifted in flow rate; local intake or vacuum leak at cylinder 2; reduced compression on cylinder 2. Test before replacing parts.
- 5
Check for recalls and service bulletins
Look up recalls for your exact vehicle with its VIN, and ask a dealer about technical service bulletins (TSBs). Manufacturers sometimes issue software updates or extended warranties for known faults.
- 6
Clear the code and verify the repair
After the repair, clear the code and drive the car under the conditions in the freeze-frame data to confirm it does not return.
P230B repair cost estimate
Estimate, not a quote. Labor times are typical ranges for this code from OBDex, and $125/hr is an assumed rate. Shop rates and labor times vary by vehicle and region. Diagnosis time may be billed separately.
- DIY difficulty
- Moderate
- Good DIY job?
- Usually a shop job
Needs a scan tool and some experience with testing.
Parts and systems involved
- Fuel injector cyl 2
- Intake manifold
- Cylinder compression
- Per cylinder lambda strategy
P230B FAQ
What does P230B mean?
P230B means “Cylinder 2 Air-Fuel Ratio Imbalance Adjustment At Limit During Balance”. The ECU continuously trims individual cylinders to equalise air-fuel ratio across the bank using ion-current or per-cylinder lambda feedback. For cylinder 2 the per-cylinder fuel correction has hit its software-side maximum or minimum without restoring balance, indicating the underlying mechanical or fuelling deviation is too large to compensate.
Is P230B serious? Can I keep driving?
We rate P230B as moderate severity. Usually yes, for a short time. The car will often drive normally, but get it diagnosed soon. Left alone it can raise fuel use and emissions and will fail an OBD inspection. If you notice rough running, warning lights flashing, overheating or a burning smell, stop driving.
What causes P230B?
The most common causes, from most to least likely: Fuel injector for cylinder 2 has drifted in flow rate; Local intake or vacuum leak at cylinder 2; Reduced compression on cylinder 2. Test before replacing parts, because several causes can set the same code.
How much does it cost to fix P230B?
Typical labor is about $125–$500 at an assumed $125/hour shop rate, plus parts. That is an estimate, not a quote: labor times and rates vary by vehicle and region, and diagnosis may be billed separately.
Can I fix P230B myself?
DIY difficulty is moderate. Most owners leave this to a shop because it needs involved testing or specialist tools. Always confirm the cause before buying parts.
Will P230B clear itself?
If the fault was intermittent, the warning may go off once the computer stops seeing it, but the code stays in memory. Fix the cause; clearing the code alone doesn’t repair anything.