What Does P02CD Mean?
The ECM has detected that Cylinder 1 fuel injector offset learning correction has reached its minimum allowable limit. This means the PCM is trying to subtract the maximum amount of fuel from Cylinder 1 to balance fueling across all cylinders, but the correction needed exceeds what the adaptive strategy can accommodate. This indicates Cylinder 1 is receiving more fuel than intended, pointing to an injector that is over-delivering or a mechanical issue causing excess fuel in that cylinder.
Common Causes
40%
Leaking or stuck-open Cylinder 1 fuel injector allowing excess fuel delivery beyond adaptive correction range
25%
Incorrect fuel injector installed in Cylinder 1 (wrong flow rate, wrong part number, or mismatched injector set)
20%
Fuel pressure regulator malfunction causing elevated rail pressure that disproportionately affects Cylinder 1 delivery
15%
Carbon buildup or mechanical deposit on Cylinder 1 injector tip altering spray pattern and effective flow rate
Diagnostic Steps
1
Step 1: Using a bidirectional scan tool, review fuel injector offset learning values for all cylinders. Compare Cylinder 1 offset against the other cylinders. A significantly negative offset on Cylinder 1 relative to others confirms over-fueling on that cylinder.
2
Step 2: Perform a relative compression test or cylinder power balance test to verify Cylinder 1 mechanical integrity. Monitor short-term and long-term fuel trims at idle and 2500 RPM to quantify the imbalance.
3
Step 3: Swap the Cylinder 1 fuel injector with an adjacent cylinder (e.g., Cylinder 3). Clear adaptive values and drive through a relearn cycle. If the fault follows the injector, replace the injector. If it stays at Cylinder 1 position, investigate mechanical causes.
4
Step 4: Measure fuel rail pressure with a mechanical gauge and compare to scan tool PID. Verify pressure is within specification (typically 35-65 PSI for port injection, 500-2900 PSI for GDI) and stable at idle.
5
Step 5: If injector tests normal, perform a cylinder leak-down test on Cylinder 1 checking for valve seal issues or piston ring blowby that could affect combustion efficiency and skew the offset learning.
Estimated Repair Cost
$150 - $600
Parts + labor, varies by vehicle and location
The ECM has detected that Cylinder 1 fuel injector offset learning correction has reached its minimum allowable limit. This means the PCM is trying to subtract the maximum amount of fuel from Cylinder 1 to balance fueling across all cylinders, but the correction needed exceeds what the adaptive stra...
The most common cause of P02CD (Cylinder 1 Fuel Injector Offset Learning At Max Limit) is: Leaking or stuck-open Cylinder 1 fuel injector allowing excess fuel delivery beyond adaptive correction range
Typical repair costs for P02CD range from $150 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Over-fueling on a single cylinder can cause catalytic converter damage from unburned fuel, increase emissions, and reduce fuel economy. Extended driving may lead to catalyst overheating or engine damage.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P02CD to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Fuel Injection System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
