What Does P050D Mean?
The PCM has detected excessive engine roughness during the cold start idle period. The crankshaft acceleration signal indicates cylinder-to-cylinder variation exceeds the acceptable threshold during the cold-start warm-up phase. The driver will notice a noticeably rough idle when starting the engine cold, with possible vibration felt through the steering wheel or vehicle body. The roughness typically improves as the engine warms up.
Common Causes
30%
Worn or fouled spark plugs that perform poorly when cold
25%
Leaking fuel injector(s) causing rich/lean cylinder imbalance during cold start
20%
Intake manifold or valve cover gasket leak that is more pronounced when components are cold
15%
Faulty ignition coil(s) with weak spark output in cold conditions
10%
Low compression in one or more cylinders due to worn valve seals or piston rings
Diagnostic Steps
1
After a cold soak, start the engine and immediately monitor misfire counters for each cylinder — identify which cylinders are contributing to the roughness.
2
Perform a relative compression test using the scan tool's cranking RPM variation analysis — this can identify a weak cylinder without removing spark plugs.
3
Remove and inspect spark plugs for wear, fouling, or incorrect gap. Replace if they are past their service interval or show signs of deposits.
4
Monitor fuel injector pulse width for each cylinder during cold start — significantly different pulse widths may indicate PCM compensation for a leaking or clogged injector.
5
After the engine warms up, compare cold idle misfire data to warm idle data — if the issue resolves when warm, focus on cold-sensitive components like spark plugs, coils, and gasket seals.
6
Perform a smoke test on the intake system while the engine is cold to identify temperature-sensitive vacuum leaks.
Estimated Repair Cost
$50 - $500
Parts + labor, varies by vehicle and location
The PCM has detected excessive engine roughness during the cold start idle period. The crankshaft acceleration signal indicates cylinder-to-cylinder variation exceeds the acceptable threshold during the cold-start warm-up phase. The driver will notice a noticeably rough idle when starting the engine...
The most common cause of P050D (Cold Start Rough Idle) is: Worn or fouled spark plugs that perform poorly when cold
Typical repair costs for P050D range from $50 to $500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The vehicle is safe to drive once warmed up. Cold start roughness is primarily an emissions and comfort issue. Allow the engine to warm up for a minute before driving aggressively. If roughness persists after warm-up, further investigation is needed.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P050D 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
Ignition / Fuel System / Cold Start
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
