Service bulletin 18-021-20

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

The communication, as NHTSA indexes it (as of 2026-10-19)
Type	Service bulletin
NHTSA id	10175154
Published by NHTSA	2020-05-18
Manufacturer's number	18-021-20
Manufacturer's date	2020-03-19
NHTSA component	ELECTRICAL SYSTEM:SOFTWARE; POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE (TCM/PCM/TECM)

NHTSA's summary

Flash: Powertrain Control Module (PCM) Updates This bulletin involves reprogramming the PCM with the latest available software. Customers may experience a Malfunction Indicator Lamp (MIL) illumination. Upon further investigation the technician may find that one or more of the following DTCs have been set:P06EF - Engine Restart Performance. P04FC - Crankcase Ventilation System Performance. P050B - Cold Start Ignition Timing Performance. P0456 - EVAP System Small Leak.If DTC P0456 is present use the wiTECH Small Leak Verification Test (SLVT) to determine if a leak is present in the system. P0128 - Thermostat Rationality. The following software enhancement is included:Enable Soot Retention for vehicles equipped with Gasoline Particulate Filter (GPF). Customer or technician may also experience the following:Unable to read data information from the OBD II connector when using a generic scan tool(APAC Only).

The document

The document is the manufacturer's. This site does not hold it. NHTSA files a document at one of these two addresses; we have not asked NHTSA which.

Components

Electrical system, Transmission and driveline, Automatic transmission, Software, Transmission control module

Trouble codes named

P0128, P0456, P04FC, P050B, P06EF

Vehicles listed
JEEP WRANGLER	2019

Listing a model year does not mean every vehicle of it is concerned: the document says which.

Other bulletins for the same vehicles and component
ReferenceY40	2024-03-18. Service bulletin. Customer Satisfaction Notification Y40 Control Module Software Updates
S2325000006	2023-08-21. Service bulletin. Customer complaint may include a MIL-on or check engine lamp on condition.
BulletinA	2023-07-31. Service bulletin. Customer Satisfaction Notification ZD7 - Radio Software Update
S1808000152	2023-04-17. Service bulletin. CEL (Check Engine Lamp) Illuminates, Recent PCM Replace or Flash Update Performed, Diagnostic Trouble Codes (DTCs) P057B Brake Pedal Position Sensor Circuit Performance, P1572 Brake Pedal Stuck, C0042-54 Brake Pedal Missing Calibration
S2207000002	2023-01-09. Service bulletin. Coolant leak
1802220	2022-10-17. Service bulletin. Flash: Powertrain Control Module (PCM) Updates This bulletin involves reprogramming the PCM with the latest available software. The customer may experience a Malfunction Indicator Lamp (MIL) illumination. Upon further investigation the technician may find one or more ofthe following DTCs:P012A - Turbocharger/Supercharger Inlet Pressure Sensor 1. P012C - Turbocharger/Supercharger Inlet Air Pressure Sensor 1 Circuit Low. P012D - Turbocharger/Supercharger Inlet Air Pressure Sensor 1 Circuit High. P0607 - ECU Internal Performance. P06EF - Engine Restart Performance. P050B - Cold Start Ignition Timing Performance. P0456 - EVAP System Small Leak.If DTC P0456 is present use the wiTECH Small Leak Verification Test (SLVT) to determine if a leak is present in the system. P0128 - Thermostat Rationality. P0507 - Idle Speed Performance Higher Than Expected. Customers may also describe the following condition:Excessive radiator fan noise when the A/C is on MAX output. In addition, the following software enhancements are available:Electric Vacuum Pump (EVP) update. Fan noise reduction.
1802120	2022-10-17. Service bulletin. Flash: Powertrain Control Module (PCM) Updates This bulletin involves reprogramming the PCM with the latest available software. Customers may experience a Malfunction Indicator Lamp (MIL) illumination. Upon further investigation the technician may find that one or more of the following DTCs have been set:P012A - Turbocharger/Supercharger Inlet Pressure Sensor 1(APAC, EMEA and LATAM Only). P012C - Turbocharger/Supercharger Inlet Air Pressure Sensor 1 Circuit Low(APAC, EMEA and LATAM Only). P012D - Turbocharger/Supercharger Inlet Air Pressure Sensor 1 Circuit High(APAC, EMEA and LATAM Only). P2C90 - Crankcase Ventilation System - Hose "A" Disconnected(APAC, EMEA and LATAM Only). P06EF - Engine Restart Performance. P04FC - Crankcase Ventilation System Performance. P050B - Cold Start Ignition Timing Performance. P0128 - Thermostat Rationality. P0456 - EVAP System Small Leak. If DTC P0456 is present, use the wiTECH Small Leak Verification Test (SLVT) to determine if there is a leak in the system. The following software enhancement is also available in this update:Enable soot retention for vehicles equipped with Gasoline Particulate Filter (GPF). Technicians may also experience the following:Unable to read data information from the OBD II connector when using a generic scan tool(APAC Only).
2400721	2022-10-17. Service bulletin. Flash: HVAC Diagnostic and System Updates This bulletin involves reprogramming the HVAC control module with the latest available software. The customer may notice one or more of the following:Intermittent change of smell or humidity level in vehicle. An intermittent blast of warm air when A/C is on. Intermittent increase of outside air through the HVAC system. In addition, the following software enhancement is also available:Improvements for customer concerns of 'cabin too warm', specifically in the mid ambient temperature range 4.5-15.5 °C (40-60 °F).
1803721	2022-09-26. Service bulletin. Flash: Powertrain Control Module (PCM) Updates This bulletin involves reprogramming the PCM with the latest available software. Customers may experience a Malfunction Indicator Lamp (MIL) illumination. Upon further investigation the technician may find that one or more of the following DTCs have been set:P02EE - Cylinder 1 Injector Circuit Performance(APAC, EMEA and LATAM Only). P02EF - Cylinder 2 Injector Circuit Performance(APAC, EMEA and LATAM Only). P02F0 - Cylinder 3 Injector Circuit Performance(APAC, EMEA and LATAM Only). P02F1 - Cylinder 4 Injector Circuit Performance(APAC, EMEA and LATAM Only). P012A - Turbocharger/Supercharger Inlet Pressure Sensor 1(APAC, EMEA and LATAM Only). P012C - Turbocharger/Supercharger Inlet Air Pressure Sensor 1 Circuit Low(APAC, EMEA and LATAM Only). P012D - Turbocharger/Supercharger Inlet Air Pressure Sensor 1 Circuit High(APAC, EMEA and LATAM Only). P2C90 - Crankcase Ventilation System - Hose "A" Disconnected(APAC, EMEA and LATAM Only). P06EF - Engine Restart Performance. P04FC - Crankcase Ventilation System Performance. P050B - Cold Start Ignition Timing Performance. P0128 - Thermostat Rationality. P0456 - EVAP System Small Leak. If DTC P0456 is present, use the wiTECH Small Leak Verification Test (SLVT) to determine if there is a leak in the system. The following software enhancement is also available in this update:Enable soot retention for vehicles equipped with Gasoline Particulate Filter (GPF). Technicians may also experience the following:Unable to read data information from the OBD II connector when using a generic scan tool(APAC Only).
08-133-21	2022-08-22. Service bulletin. UAQ and UCQ Radio Enhancements This bulletin involves inspecting and if required, updating the radio software level to: 39.6.The repair procedure must be followed step by step. If the radio is not updated with the correct software level at the correct time the radio can be damaged. If the radio was damaged by not following the repairprocedure the radio may need to be replaced. Customers may experience one or more of the following: Lost radio presets. SXM favorite song not displaying/playing. Radio display screen is black, intermittent. Radio freeze intermittent. Incorrect navigation address/location/directions. Bluetooth pair or connection issue. Radio channel change by itself. SXM icon inoperative. Backup camera has black display screen. High pitch chime noise. Contact list not loading. Device not supported message. Remote app inoperative. Travel-Link fuel price incorrect. Backup camera gridlines missing. Unable to adjust volume. In addition the following enhancements are included: Heavy Duty (HD)Truck USB HUB improvements. HD Truck heated steering wheel improvements.