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Service bulletins for the 2018 Jeep Wrangler

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.

716 on file from NHTSA, as of 2026-10-19.

About P0128 on the 2018 Jeep Wrangler: what the code means, and the bulletins and recalls about the same components.

By type

By component

By trouble code

Only bulletins with trouble code: P0128 are shown. Show all

Bulletins, newest first
18014202022-10-17. Service bulletin. POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE (TCM/PCM/TECM). 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:P2C90 - Crankcase Ventilation System - Hose "A" Disconnected(APAC, EMEA and LATAM Only). P04FC - Crankcase Ventilation System Performance(APAC, EMEA and LATAM Only). P2453 - Particulate Filter Pressure Sensor "A" Circuit Range/Performance(APAC and EMEA only equipped with Gas Particulate Filter (GPF). P245F - Particulate Filter Pressure Sensor "B" Circuit Range/Performance(APAC and EMEA only equipped with Gas Particulate Filter (GPF). P0456 - EVAP System Small Leak. If DTC P0456 is present use wiTECH Small Leak Verification Test (SLVT) to determine if a leak is present in the system. P0171 - Fuel System 1/1 Lean(LATAM Only). P0172 - Fuel System 1/1 Rich(LATAM Only). P0128 - Thermostat Rationality(Sales Codes NA1 with NBQ or NB6 Only - APAC and EMEA Only). P050B - Cold Start Ignition Timing Performance(Sales Codes NA1 with NBQ or NB6 Only - APAC and EMEA Only). Customers may comment on one or more of the following:Excessive fan noise when the A/C is on MAX output. Rough idle at engine start up in colder ambient temperatures. Software enhancements also included in this update:Electric Vacuum Pump (EVP) update. Fan noise reduction. Low Speed Pre Ignition (LSPI) update.
18-036-212021-05-24. Service bulletin. FUEL SYSTEM, GASOLINE; BACK OVER PREVENTION; ELECTRICAL SYSTEM; EXTERIOR LIGHTING; SERVICE BRAKES. 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). P2C90 - Crankcase Ventilation System - Hose "A" Disconnected(APAC, EMEA and LATAM Only). P04FC - Crankcase Ventilation System Performance(APAC, EMEA and LATAM Only). P2453 - Particulate Filter Pressure Sensor "A" Circuit Range/Performance(APAC and EMEA only equipped with Gas Particulate Filter(GPF)). P245F - Particulate Filter Pressure Sensor "B" Circuit Range/Performance(APAC and EMEA only equipped with Gas Particulate Filter (GPF)). P0456 - EVAP System Small Leak.If DTC P0456 is present use wiTECH Small Leak Verification Test (SLVT) to determine if a leak is present in the system. P0171 - Fuel System 1/1 Lean(LATAM Only). P0172 - Fuel System 1/1 Rich(LATAM Only). P0128 - Thermostat Rationality(Sales Codes NA1 with NBQ or NB6 Only - APAC and EMEA Only). P050B - Cold Start Ignition Timing Performance(Sales Codes NA1 with NBQ or NB6 Only - APAC and EMEA Only). Customers may comment on one or more of the following:Excessive fan noise when the A/C is on MAX output. Rough idle at engine start up in colder ambient temperatures. The following software enhancements are also included in this update:Electric Vacuum Pump (EVP) update. Fan noise reduction. Low Speed Pre Ignition (LSPI) update.
18-014-20 REV. B2020-07-27. Service bulletin. ELECTRICAL SYSTEM; ENGINE AND ENGINE COOLING; POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE (TCM/PCM/TECM). 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:P2C90 - Crankcase Ventilation System - Hose "A" Disconnected(APAC, EMEA and LATAM Only). P04FC - Crankcase Ventilation System Performance(APAC, EMEA and LATAM Only). P2453 - Particulate Filter Pressure Sensor "A" Circuit Range/Performance(APAC and EMEA only equipped with Gas Particulate Filter (GPF). P245F - Particulate Filter Pressure Sensor "B" Circuit Range/Performance(APAC and EMEA only equipped with Gas Particulate Filter (GPF). P0456 - EVAP System Small Leak. If DTC P0456 is present use wiTECH Small Leak Verification Test (SLVT) to determine if a leak is present in the system. P0171 - Fuel System 1/1 Lean(LATAM Only). P0172 - Fuel System 1/1 Rich(LATAM Only). P0128 - Thermostat Rationality(Sales Codes NA1 with NBQ or NB6 Only - APAC and EMEA Only). P050B - Cold Start Ignition Timing Performance(Sales Codes NA1 with NBQ or NB6 Only - APAC and EMEA Only). Customers may comment on one or more of the following:Excessive fan noise when the A/C is on MAX output. Rough idle at engine start up in colder ambient temperatures. Software enhancements also included in this update:Electric Vacuum Pump (EVP) update. Fan noise reduction. Low Speed Pre Ignition (LSPI) update.
18-014-20 REV. A2020-05-26. Service bulletin. FUEL SYSTEM, GASOLINE; EXTERIOR LIGHTING; ELECTRICAL SYSTEM; BACK OVER PREVENTION. 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:P0456 - EVAP System Small Leak.If DTC P0456 is present use wiTECH Small Leak Verification Test (SLVT) to determine if a leak is present in the system. P0171 - Fuel System 1/1 Lean(LATAM Only). P0172 - Fuel System 1/1 Rich(LATAM Only). P0128 - Thermostat Rationality(APAC&EMEA with Sales Codes NA1 with NBQ or NB6 Only). P050B - Cold Start Ignition Timing Performance(APAC&EMEA with Sales Codes NA1 with NBQ or NB6 Only). Customers may experience:Excessive fan noise when the A/C is on MAX output. Rough idle at engine start up in colder ambient emperatures. Software enhancements include:Electric Vacuum Pump (EVP) update. Fan noise reduction. Low Speed Pre Ignition (LSPI) update.
18-014-20 REV. A2020-05-18. Service bulletin. POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE (TCM/PCM/TECM). 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:P0456 - EVAP System Small Leak.If DTC P0456 is present use wiTECH Small Leak Verification Test (SLVT) to determine if a leak is present in the system. P0171 - Fuel System 1/1 Lean(LATAM Only). P0172 - Fuel System 1/1 Rich(LATAM Only). P0128 - Thermostat Rationality(APAC&EMEA with Sales Codes NA1 with NBQ or NB6 Only). P050B - Cold Start Ignition Timing Performance(APAC&EMEA with Sales Codes NA1 with NBQ or NB6 Only). Customers may experience:Excessive fan noise when the A/C is on MAX output. Rough idle at engine start up in colder ambient emperatures. Software enhancements include:Electric Vacuum Pump (EVP) update. Fan noise reduction. Low Speed Pre Ignition (LSPI) update.
18-014-20 REV. A2020-04-27. Service bulletin. ELECTRICAL SYSTEM; POWER TRAIN. 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:P0456 - EVAP System Small Leak.If DTC P0456 is present use wiTECH Small Leak Verification Test (SLVT) to determine if a leak is present in the system. P0171 - Fuel System 1/1 Lean(LATAM Only). P0172 - Fuel System 1/1 Rich(LATAM Only). P0128 - Thermostat Rationality(APAC&EMEA with Sales Codes NA1 with NBQ or NB6 Only). P050B - Cold Start Ignition Timing Performance(APAC&EMEA with Sales Codes NA1 with NBQ or NB6 Only). Customers may experience:Excessive fan noise when the A/C is on MAX output. Rough idle at engine start up in colder ambient emperatures. Software enhancements include:Electric Vacuum Pump (EVP) update. Fan noise reduction. Low Speed Pre Ignition (LSPI) update.
18-014-202020-04-06. Service bulletin. POWER TRAIN; ELECTRICAL SYSTEM:SOFTWARE. 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:P0456 - EVAP System Small Leak.If DTC P0456 is present use wiTECH Small Leak Verification Test (SLVT)to determine if a leak is present in the system. P0128 - Thermostat Rationality(APAC&EMEA with Sales Codes NA1 with NBQ or NB6 Only). P050B - Cold Start Ignition Timing Performance(APAC&EMEA with Sales Codes NA1 with NBQ or NB6 Only). Customers may experience:Excessive fan noise when the A/C is on MAX output. Rough idle at engine start up in colder ambient temperatures. Software enhancements include:Electric Vacuum Pump (EVP) update. Fan noise reduction. Low Speed Pre Ignition (LSPI) update.
18-041-192019-07-15. Service bulletin. POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE (TCM/PCM/TECM). Flash: Powertrain Control Module (PCM) Updates This bulletin involves reprogramming the Powertrain Control Module (PCM) with thelatest available software. Customers may experience a Malfunction Indicator Lamp (MIL) illumination. Upon further investigation the technician may find that one or moreof the following DTCs have been set: P0456 - EVAP System Small Leak(APAC&EMEA with Sales Codes NA1 with NBQ or NB6 Only). P0128 - Thermostat Rationality(APAC&EMEA with Sales Codes NA1 with NBQ or NB6 Only). P050B - Cold Start Ignition Timing Performance(APAC&EMEA with Sales Codes NA1 with NBQ or NB6 Only). Customers may experience: Excessive fan noise when the A/C is on MAX output. Rough idle at engine start up in colder ambient temperatures. Software enhancements include:Electric vacuum pump (EVP) update. Fan noise reduction. Low speed pre ignition (LSPI) update.

The summaries are NHTSA's. Each bulletin's page links NHTSA's copy of the manufacturer's document.