What Does P02BA Mean?
The ECM has detected that the individual fuel trim correction for cylinder 9 has reached its maximum enrichment limit. The system is adding the maximum allowable fuel to cylinder 9 but still cannot achieve a proper air/fuel ratio, indicating a severe lean condition. This code applies to engines with 9 or more cylinders (V10, V12, radial, etc.). The driver may notice misfire, rough running, and power loss.
Common Causes
30%
Clogged or partially restricted cylinder 9 fuel injector unable to deliver adequate fuel volume
25%
Vacuum leak at the cylinder 9 intake runner gasket or port allowing unmetered air entry
20%
Faulty cylinder 9 injector electrical circuit reducing pulse width or causing intermittent operation
15%
Low fuel pressure at the rail or secondary rail supplying the rear bank, causing inadequate delivery
10%
Exhaust leak near the cylinder 9 port causing false lean O2 sensor readings
Diagnostic Steps
1
Review live data for cylinder 9 individual fuel trim — confirm it is at or near the maximum positive correction limit (typically +25% to +30%).
2
Perform a smoke test on the intake manifold focusing on the cylinder 9 intake runner and gasket surfaces to locate any vacuum leak.
3
Run an injector balance test by disabling each injector individually and comparing rpm drops — cylinder 9 should produce a similar drop as the others.
4
Check fuel rail pressure at key-on engine-off and at idle; on multi-rail systems, verify pressure at both rails to ensure the rail feeding cylinder 9 is not restricted.
5
Inspect the cylinder 9 injector connector for corrosion or damage, and measure injector resistance (typically 11-17 ohms for high-impedance injectors).
Estimated Repair Cost
$200 - $600
Parts + labor, varies by vehicle and location
The ECM has detected that the individual fuel trim correction for cylinder 9 has reached its maximum enrichment limit. The system is adding the maximum allowable fuel to cylinder 9 but still cannot achieve a proper air/fuel ratio, indicating a severe lean condition. This code applies to engines with...
The most common cause of P02BA (Cylinder 9 - Fuel Trim at Max Limit) is: Clogged or partially restricted cylinder 9 fuel injector unable to deliver adequate fuel volume
Typical repair costs for P02BA range from $200 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Driveable short distances but extended driving is not recommended. The lean condition on cylinder 9 causes elevated combustion temperatures risking catalytic converter damage and potential detonation-induced engine damage.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P02BA to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel System
Difficulty
Type
Generic (SAE)
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