# P1D90 on the 2021 Ram 1500

The bulletins listed name this code in NHTSA's summary, or are about the same components. A bulletin or a recall listed here may apply to the model year. None of it is a diagnosis.

This code is specific to a manufacturer and is not described here.

## Bulletins for this model year that name P1D90

- [11030138](https://open.wenmarpro.com/bulletins/11030138), 2026-03-18: The vehicle will exhibit a service transmission/check engine warning indicator for the following transmission models: 845RE, 8HP45, 850RE, 8HP50, 8HP70, 8HP75, 8HP75\-PHEV, 8HP75\-LCV, 8HP90, 8HP95. Transmissions may exhibit the following diagnostic codes: P07E4, P1DB2, P0716, P1B14, P0733, P1D90, P1DB7, P1B13.
- [11029770](https://open.wenmarpro.com/bulletins/11029770), 2026-03-05: Service transmission/check engine warning indicator for the 850RE, 8HP50, 8HP70, 8HP75, 8HP75\-PHEV transmissions that have fault codes P07E4, P1DB2, P0716, P1B14, P0733, P1D90, P1DB7, P1B13.
- [10220988](https://open.wenmarpro.com/bulletins/10220988), 2022-09-26: Transmission Oil Cooler Lines Not Fully Connected This bulletin involves inspecting the Transmission Oil Cooler \(TOC\) lines and reconnectingif necessary. Customers may experience a Malfunction Indicator Lamp \(MIL\) illumination. Upon further investigation the technician may find one or more ofthe following Diagnostic Trouble Codes \(DTCs\). P1D90\-00 Incorrect Gear Ratio \- Clutch 2 Defective. P1D91\-00 Incorrect Gear Ratio \- Clutch 3 Defective. P1D92\-00 Incorrect Gear Ratio \- Clutch 4 Defective. P1D93\-00 Incorrect Gear Ratio \- Clutch 5 Defective. P1D95\-00 Tcm Clutch Failure Undetermined. P1B14\-00 Park\-By\-Wire \- Unintended Park Position. P1B13\-00 Park\-By\-Wire \- Unintended Out Of Park Position. P1D99\-00 Incorrect Gear Ratio: Clutch B Or E Defective. P1D9A\-00 Incorrect Gear Ratio: Clutch C Or D Defective. P1D95\-00 Tcm Clutch Failure Undetermined. P07E4\-00 Unable To Engage Park. P1DCD\-00 Tcm Monitoring Processor Performance \- Multiple Clutches Locked Up. P0735\-00 Gear 5 Shift Incorrect Ratio. P0919\-00 Gear Shift Position Control Error. Customers may also experience the following:Transmission fluid leaking under vehicle. The vehicle will not shift. Slow shifting between gears.
- [10220987](https://open.wenmarpro.com/bulletins/10220987), 2022-09-26: Transmission Oil Cooler Lines Not Fully Connected This bulletin involves inspecting the Transmission Oil Cooler \(TOC\) lines and reconnecting if necessary. Customers may experience a Malfunction Indicator Lamp \(MIL\) illumination. Upon further investigation the technician may find one or more ofthe following Diagnostic Trouble Codes \(DTCs\). P1D90\-00 Incorrect Gear Ratio \- Clutch 2 Defective. P1D91\-00 Incorrect Gear Ratio \- Clutch 3 Defective. P1D92\-00 Incorrect Gear Ratio \- Clutch 4 Defective. P1D93\-00 Incorrect Gear Ratio \- Clutch 5 Defective. P1D95\-00 Tcm Clutch Failure Undetermined. P1B14\-00 Park\-By\-Wire \- Unintended Park Position. P1B13\-00 Park\-By\-Wire \- Unintended Out Of Park Position. P1D99\-00 Incorrect Gear Ratio: Clutch B Or E Defective. P1D9A\-00 Incorrect Gear Ratio: Clutch C Or D Defective. P1D95\-00 Tcm Clutch Failure Undetermined. P07E4\-00 Unable To Engage Park. P1DCD\-00 Tcm Monitoring Processor Performance \- Multiple Clutches Locked Up. P0735\-00 Gear 5 Shift Incorrect Ratio. P0919\-00 Gear Shift Position Control Error. Customers may also experience the following:Transmission fluid leaking under vehicle. The vehicle will not shift. Slow shifting between gears.
- [10190735](https://open.wenmarpro.com/bulletins/10190735), 2021-04-26: Transmission Oil Cooler Lines Not Fully Connected This bulletin involves inspecting the Transmission Oil Cooler \(TOC\) lines and reconnectingif necessary. Customers may experience a Malfunction Indicator Lamp \(MIL\) illumination. Upon further investigation the technician may find one or more ofthe following Diagnostic Trouble Codes \(DTCs\). P1D90\-00 Incorrect Gear Ratio \- Clutch 2 Defective. P1D91\-00 Incorrect Gear Ratio \- Clutch 3 Defective. P1D92\-00 Incorrect Gear Ratio \- Clutch 4 Defective. P1D93\-00 Incorrect Gear Ratio \- Clutch 5 Defective. P1D95\-00 Tcm Clutch Failure Undetermined. P1B14\-00 Park\-By\-Wire \- Unintended Park Position. P1B13\-00 Park\-By\-Wire \- Unintended Out Of Park Position. P1D99\-00 Incorrect Gear Ratio: Clutch B Or E Defective. P1D9A\-00 Incorrect Gear Ratio: Clutch C Or D Defective. P1D95\-00 Tcm Clutch Failure Undetermined. P07E4\-00 Unable To Engage Park. P1DCD\-00 Tcm Monitoring Processor Performance \- Multiple Clutches Locked Up. P0735\-00 Gear 5 Shift Incorrect Ratio. P0919\-00 Gear Shift Position Control Error. Customers may also experience the following:Transmission fluid leaking under vehicle. The vehicle will not shift. Slow shifting between gears.
- [10190734](https://open.wenmarpro.com/bulletins/10190734), 2021-04-26: Transmission Oil Cooler Lines Not Fully Connected This bulletin involves inspecting the Transmission Oil Cooler \(TOC\) lines and reconnecting if necessary. Customers may experience a Malfunction Indicator Lamp \(MIL\) illumination. Upon further investigation the technician may find one or more ofthe following Diagnostic Trouble Codes \(DTCs\). P1D90\-00 Incorrect Gear Ratio \- Clutch 2 Defective. P1D91\-00 Incorrect Gear Ratio \- Clutch 3 Defective. P1D92\-00 Incorrect Gear Ratio \- Clutch 4 Defective. P1D93\-00 Incorrect Gear Ratio \- Clutch 5 Defective. P1D95\-00 Tcm Clutch Failure Undetermined. P1B14\-00 Park\-By\-Wire \- Unintended Park Position. P1B13\-00 Park\-By\-Wire \- Unintended Out Of Park Position. P1D99\-00 Incorrect Gear Ratio: Clutch B Or E Defective. P1D9A\-00 Incorrect Gear Ratio: Clutch C Or D Defective. P1D95\-00 Tcm Clutch Failure Undetermined. P07E4\-00 Unable To Engage Park. P1DCD\-00 Tcm Monitoring Processor Performance \- Multiple Clutches Locked Up. P0735\-00 Gear 5 Shift Incorrect Ratio. P0919\-00 Gear Shift Position Control Error. Customers may also experience the following:Transmission fluid leaking under vehicle. The vehicle will not shift. Slow shifting between gears.
- [10187717](https://open.wenmarpro.com/bulletins/10187717), 2021-03-01: Transmission Oil Cooler Line Not Fully Connected This bulletin involves inspecting the Transmission Oil Cooler \(TOC\) lines and reconnectingif necessary. Customers may experience a Malfunction Indicator Lamp \(MIL\) illumination. Upon further investigation the technician may find one or more ofthe following Diagnostic Trouble Codes \(DTCs\).P1D90\-00 Incorrect Gear Ratio \- Clutch 2 Defective. P1D91\-00 Incorrect Gear Ratio \- Clutch 3 Defective. P1D92\-00 Incorrect Gear Ratio \- Clutch 4 Defective. P1D93\-00 Incorrect Gear Ratio \- Clutch 5 Defective. P1D95\-00 Tcm Clutch Failure Undetermined. P1B14\-00 Park\-By\-Wire \- Unintended Park Position. P1B13\-00 Park\-By\-Wire \- Unintended Out Of Park Position. P1D99\-00 Incorrect Gear Ratio: Clutch B Or E Defective. P1D9A\-00 Incorrect Gear Ratio: Clutch C Or D Defective. P1D95\-00 Tcm Clutch Failure Undetermined. P07E4\-00 Unable To Engage Park. P1DCD\-00 Tcm Monitoring Processor Performance \- Multiple Clutches Locked Up. P0735\-00 Gear 5 Shift Incorrect Ratio. P0919\-00 Gear Shift Position Control Error. Customers may also experience the following:Transmission fluid leaking under vehicle. The vehicle will not shift. Slow shifting between gears.