Faulty or contaminated fuel injector for cylinder 1 causing delayed closing or spray pattern issues; Wiring harness damage or poor electrical connection at the cylinder 1 injector; Sticking or failed fuel injector solenoid; Low fuel pressure or restricted fuel flow affecting injector response; Contaminated engine oil or incorrect oil viscosity affecting hydraulic lash adjusters or variable valve timing components; Camshaft or crankshaft position sensor signal interference or early wear; Internal engine mechanical wear affecting the injection timing relationship

DTC codes / P01xx · Fuel and air metering / P01CC

P01CCCylinder 1 Injection Timing Performance - Over Advanced

Q: What does code P01CC mean?

Cylinder 1 Injection Timing Performance - Over Advanced. P01CC indicates that the powertrain control module has detected the fuel injection timing for cylinder 1 is more advanced than the commanded value during its self-test. The engine computer sees the actual injection event happening too early compared with what it expects, which can upset combustion timing and emissions.

P01CC indicates that the powertrain control module has detected the fuel injection timing for cylinder 1 is more advanced than the commanded value during its self-test. The engine computer sees the actual injection event happening too early compared with what it expects, which can upset combustion timing and emissions.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyProfessional

AreaFuel and air metering

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Rough idle or slight engine misfire that may be intermittent
Reduced fuel economy as the computer adjusts injection strategy
Hesitation or stumble during acceleration
Increased exhaust emissions or a sulfur smell from the exhaust
In severe cases, engine knock or pinging under load

Common causes, most likely first

Faulty or contaminated fuel injector for cylinder 1 causing delayed closing or spray pattern issues
Wiring harness damage or poor electrical connection at the cylinder 1 injector
Sticking or failed fuel injector solenoid
Low fuel pressure or restricted fuel flow affecting injector response
Contaminated engine oil or incorrect oil viscosity affecting hydraulic lash adjusters or variable valve timing components
Camshaft or crankshaft position sensor signal interference or early wear
Internal engine mechanical wear affecting the injection timing relationship

How to diagnose and fix it

Connect a scan tool and verify the code is current, then check for any related pending or history codes
Inspect the cylinder 1 fuel injector electrical connector and harness for corrosion, chafing, or loose pins
Measure fuel injector resistance and compare with the manufacturer's specification
Perform a fuel pressure test to rule out low pressure or volume issues
Use a lab scope to compare the injector command pulse from the PCM with the actual injector current ramp
Check engine oil condition and level, and verify the correct viscosity is used
If all electrical and fuel checks pass, perform a compression test and cylinder leak-down test to assess mechanical condition

Over-Advanced Timing Isn't Always the Injector

A dirty or failing mass airflow sensor can skew the PCM's fueling calculations and indirectly cause an over-advanced injection timing code for cylinder 1.
Excessive carbon buildup on the injector tip can delay injector closing, making the effective injection timing appear advanced even when the solenoid is electrically sound.
A weak battery or charging system can cause voltage drops that affect injector response time, triggering this code without any hard injector failure.
The code can be set by a momentary glitch in the camshaft position sensor signal that does not store a separate cam sensor code, so always check sensor waveforms.
After repairs, the adaptive injection timing values must be reset with a scan tool, or the code may reappear until the PCM relearns.

Can I keep driving with P01CC?

You can usually drive the vehicle short distances to a repair shop, but avoid heavy acceleration or towing until the fault is diagnosed. Prolonged driving with over-advanced injection timing can lead to engine knock, overheating, and catalytic converter damage.

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.