P050D Cold start rough idle

Cold start rough idle

P050D in short

P050D means the engine computer saw the engine run unevenly during the first moments after a cold start, usually from uneven fuel delivery. Faulty fuel injectors are a common cause, and several makers have software updates. Check for bulletins, then have the injectors and fuel pressure tested. Get it inspected soon, especially if a misfire code also sets.

Right after a cold start, many direct-injection engines run a special mode, such as GM's dual-pulse injection, to warm the catalytic converter quickly. The engine computer watches crankshaft speed for uneven firing during that time.

On GM engines the test runs once per cold start, while the catalytic converter is still cold. If crankshaft speed varies too much, the computer sets P050D and turns the special mode off for that trip.

The usual reasons are a restricted or leaking injector, low fuel pressure, poor fuel, or a voltage drop while cranking. Several GM and Chrysler models also have software fixes or engine-specific bulletins.

Most likely causes

  1. Restricted or faulty fuel injector

    Common general cause
    Why it ranks here
    GM's service information names a restricted injector as a cause and ends its test with injector replacement. Owners of GM trucks and SUVs report injectors replaced for P050D, and GM says matched injectors on some engines must be replaced as a set.
    What would change this
    Rises if misfire counts during the first cold start point to one cylinder, or an injector fails a balance test.
    How to test the fuel injector

  2. Engine computer software (some models)

    Supported by vehicle data
    Why it ranks here
    GM (2016-2017 Volt, 2020 Colorado and Canyon, 2024-2025 Traverse, Acadia and Enclave) and Chrysler (2008 300 and Charger) fix P050D with a computer update.
    What would change this
    Rises if a bulletin covers your vehicle and the update has not been done.
    How to test the engine control module (ecm / pcm)

  3. Low fuel pressure or contaminated fuel

    Possible — needs testing
    Why it ranks here
    GM's test checks fuel pressure and fuel quality before blaming injectors, because either can starve cylinders during the cold start.
    What would change this
    Rises if fuel pressure is low or the fuel is contaminated; falls if both test good.
    How to test the fuel pump

  4. Voltage drop during cold start

    Possible — needs testing
    Why it ranks here
    GM lists a voltage drop during cold start as a diagnostic aid, since weak voltage affects injector operation.
    What would change this
    Rises with a weak battery or poor battery connections.

  5. Coolant leaking into the cylinders (GM V8 engines)

    Supported by vehicle data
    Why it ranks here
    GM links P050D with P0300 after a cold start, white smoke and coolant odour to coolant getting into the cylinders on 2014-2020 trucks, SUVs and cars.
    What would change this
    Rises with white smoke at cold start, coolant smell or a falling coolant level.

  6. Exhaust-side valve lash adjusters (some GM four-cylinder engines)

    Supported by vehicle data
    Why it ranks here
    GM tells technicians, after the normal diagnostic fails to find a cause on 2016-2018 Cruze, Malibu, Volt and others, to replace only the exhaust-side lash adjusters.
    What would change this
    Applies to the listed vehicles, and only after the normal diagnostic.

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Read all stored codes and freeze-frame data, and note whether a misfire code (P0300-P0308) names a cylinder. Check the coolant level with the engine cold and watch the exhaust at the next cold start.

    Low riskTool: scan tool

  2. Ask a dealer, or check a bulletin database, for software updates or bulletins for P050D on your vehicle, and have the battery tested.

    Low riskTool: VIN, battery tester

  3. Have a shop check misfire counters during a cold start, measure fuel pressure, check fuel quality and test the injectors.

    Best left to a shopTool: scan tool, fuel pressure gauge, injector tester

    Warning:Direct-injection fuel systems run at very high pressure; opening them without the right tools is a fire and injury risk. Leave this to a shop.

Symptoms

  • Rough or shaky idle for the first minute after a cold start
  • Hesitation pulling away from a cold start
  • Check engine light, often with a misfire code
  • White smoke or coolant smell from the exhaust Gets more serious: stop and have it checked.
  • Check engine light flashing Gets more serious: stop and have it checked.

Compare with: Rough idle with the check engine light on, Car shaking with the check engine light on

How to fix

  1. Write down every stored code and the freeze-frame data before clearing anything.

  2. Ask a dealer whether a software update or bulletin covers P050D on your vehicle before replacing parts.

  3. Have the battery and its connections checked; weak voltage during cranking can contribute.

Parts and cost context

  • Fuel injector:On some GM engines the injectors are flow-matched, so GM says all must be replaced together if any one needs replacing.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Chevrolet

  • 2014–2020 · Silverado 1500

    Supported by vehicle data

    With P050D and white smoke or coolant odour after a cold start, GM points to coolant getting into the cylinders (PIP5498M). Owners also report injectors replaced for P050D.

  • 2024–2025 · Traverse

    Supported by vehicle data

    GM has a PCM update for cold start rough idle with P050D, and says injectors must be replaced as a matched set (24-NA-244, PIP5993C).

  • 2020 · Colorado

    Supported by vehicle data

    GM has an engine computer calibration for P050D (21NA104).

  • 2016–2017 · Volt

    Supported by vehicle data

    GM reprograms the engine computer for misfire and rough or high idle with P050D (32340B).

  • 2016–2018 · Cruze

    Supported by vehicle data

    If the normal diagnostic finds nothing, GM points to the exhaust-side lash adjusters (PIP5472F).

  • PIP5498MStatus unverified

    GM PIP5498M: P050D and P0300 after cold start, coolant in cylinders

    2014–2020silverado-1500, tahoe, suburban · issued · NHTSA 10179646

    P050D with P0300 after a cold start, with white smoke or coolant odour, caused by coolant getting into the cylinders. Also lists Sierra, Yukon, Escalade, Camaro, Corvette and CTS.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • PIP5472FStatus unverified

    GM PIP5472F: P050D, exhaust-side lash adjusters

    2016–2018cruze, malibu, volt · issued · NHTSA 10156905

    Run the normal diagnostic first; if it does not find the cause, replace only the exhaust-side lash adjusters. Also lists Spark, Encore, and 2018 Equinox and Terrain.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • PIP5993CStatus unverified

    GM PIP5993C: P050D cold start misfire, replace injectors as a set

    2024–2025traverse · issued · NHTSA 11011185

    If any injector needs replacing for P050D, replace all of them together because flow rates are matched. Also covers Acadia and 2025 Enclave.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 24-NA-244Status unverified

    GM 24-NA-244: PCM programming for cold start rough idle with P050D

    2024–2025traverse · issued · NHTSA 11019745

    Program the PCM with the latest software. Also covers Acadia and 2025 Enclave.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 21NA104Status unverified

    GM 21-NA-104: ECM calibration for P050D

    2020colorado · issued · NHTSA 10194115

    Engine computer calibration for P050D on the 2020 Colorado and Canyon.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 32340BStatus unverified

    GM 32340B: Volt misfire, rough or high idle, P0300 or P050D

    2016–2017volt · issued · NHTSA 10137763

    Engine misfire with rough or high idle and P0300 or P050D; dealers reprogram the engine computer.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

GMC

  • 2024–2025 · Acadia

    Supported by vehicle data

    GM has a PCM update for cold start rough idle with P050D, and says injectors must be replaced as a matched set (24-NA-244, PIP5993C).

  • 2020 · Canyon

    Supported by vehicle data

    GM has an engine computer calibration for P050D (21NA104).

  • PIP5993CStatus unverified

    GM PIP5993C: P050D cold start misfire, replace injectors as a set

    2024–2025traverse · issued · NHTSA 11011185

    If any injector needs replacing for P050D, replace all of them together because flow rates are matched. Also covers Acadia and 2025 Enclave.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 24-NA-244Status unverified

    GM 24-NA-244: PCM programming for cold start rough idle with P050D

    2024–2025traverse · issued · NHTSA 11019745

    Program the PCM with the latest software. Also covers Acadia and 2025 Enclave.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 21NA104Status unverified

    GM 21-NA-104: ECM calibration for P050D

    2020colorado · issued · NHTSA 10194115

    Engine computer calibration for P050D on the 2020 Colorado and Canyon.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Buick

  • 24-NA-244Status unverified

    GM 24-NA-244: PCM programming for cold start rough idle with P050D

    2024–2025traverse · issued · NHTSA 11019745

    Program the PCM with the latest software. Also covers Acadia and 2025 Enclave.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Chrysler

  • 1804807Status unverified

    Chrysler PCM flash: P050D cold start rough idle

    2008300 · issued · NHTSA 10023640

    PCM flash for P050D with cold start rough idle or a delay at initial tip-in from a stop. Also covers the 2008 Dodge Charger and Magnum.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Dodge

  • 1804807Status unverified

    Chrysler PCM flash: P050D cold start rough idle

    2008300 · issued · NHTSA 10023640

    PCM flash for P050D with cold start rough idle or a delay at initial tip-in from a stop. Also covers the 2008 Dodge Charger and Magnum.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • P0300Random or multiple-cylinder misfire detected

    Shares causes Supported by vehicle data

    P050D often sets with P0300 or a cylinder misfire code after a cold start, from the same uneven fuelling.

  • P0420Catalytic converter efficiency below the computer's limit (Bank 1)

    Primary / secondary Common general cause

    Likely primary: P050D. Repeated cold-start misfire sends unburned fuel to the catalytic converter, which can overheat it and later set P0420.

All Vehicle speed, idle control and engine electrical codes

P050D questions

Do I need to replace all the injectors for P050D?

Not usually, but on 2024-2025 Traverse, Acadia and Enclave GM says that if any injector is replaced, all must be, because their flow rates are matched. Follow the service information for your engine.

Sources and review

  1. 2011 Saab 9-4X V6 (GM): DTC P050D Cold Start Rough Idle — General Motors / Saab Automobile (read via saabwisonline.com)
  2. GM PIP5498M: P050D and P0300 after cold start, coolant in cylinders — General Motors / NHTSA ,
  3. NHTSA complaint ODI 11648441: 2025 Chevrolet Traverse, P0300/P050D, cylinder 4 injector at 120 miles — NHTSA Office of Defects Investigation (complaint flat file) ,
  4. Cal. Code Regs. tit. 13, § 1968.2 - Malfunction and Diagnostic System Requirements (OBD II) — California Air Resources Board (via Cornell LII)
  5. Do you drive a 1996 or newer car or light truck? (On-Board Diagnostics, EPA420-F-02-016) — U.S. Environmental Protection Agency
  6. 2023 Integra Owner's Manual: Indicator, Coming On/Blinking — American Honda Motor Co.
  7. 2023 Integra Owner's Manual: How to Handle Overheating — American Honda Motor Co.
  8. GM PIP5993C: P050D cold start misfire, replace all injectors together — General Motors / NHTSA ,
  9. NHTSA complaint ODI 11290127: 2016 Chevrolet Silverado 1500, P050D, two injectors replaced — NHTSA Office of Defects Investigation (complaint flat file) ,
  10. NHTSA complaint ODI 11319257: 2017 Chevrolet Silverado, P050D rough idle at startup, injectors — NHTSA Office of Defects Investigation (complaint flat file) ,
  11. GM 32340B: Volt misfire, rough or high idle, P0300 or P050D — General Motors / NHTSA ,
  12. GM 21-NA-104: ECM calibration for P050D — General Motors / NHTSA ,
  13. GM 24-NA-244: PCM programming for cold start rough idle with P050D — General Motors / NHTSA ,
  14. Chrysler bulletin 1804807: PCM flash for P050D cold start rough idle — Chrysler LLC / NHTSA ,
  15. GM PIP5472F: P050D, replace exhaust-side lash adjusters if SI diagnosis fails — General Motors / NHTSA ,
  16. What You Should Know About Catalytic Converters — AA1Car.com (Larry Carley, automotive technical writer)
Last reviewed
Written by
Saurabh K.
Editorial review
Pending
Technician review
Technician review pending

This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error

My Car

Pick your car and code pages will point out notes and bulletins for it. Saved only in this browser.

Fill this in from your VIN

Used once to identify your engine; not stored.