Restore Smooth Shifting to Your Chevy HHR
If your 2006-2011 Chevrolet HHR is suffering from harsh shifting, getting stuck in gear, or has an illuminated check engine light, a faulty Transmission Control Module (TCM) is the most likely cause. As an automotive technician with over two decades of experience, I’ve seen countless GM vehicles, especially the HHR, come into the shop with these exact symptoms. The T42 TCM is the electronic brain of your automatic transmission, and when it fails, it can make your vehicle unreliable and frustrating to drive. This replacement module is the definitive solution, arriving pre-programmed to your vehicle’s specific VIN for a true plug-and-play repair.
A Technician’s Notebook
I remember a 2009 HHR that came in with an intermittent ‘stuck in 3rd gear’ complaint and a persistent P0700 code. The owner had already spent a fair amount of money replacing a couple of shift solenoids, but the problem kept returning. After a quick check of the wiring harness for any obvious damage, we focused on the TCM. These modules, located in the hot engine bay, often fail internally from years of heat cycles. We installed one of our VIN-programmed T42 units, cleared the codes, and the car’s shifting was instantly crisp and correct. It’s a classic case where chasing individual solenoid codes can be misleading when the controller itself is the root of the problem.
Why a Pre-Programmed 2006-2011 HHR Transmission Module is the Smart Choice
The biggest hurdle in replacing a modern vehicle module is the need for dealership-level programming. Our process eliminates that step entirely. We flash the module with the latest GM software updates using your vehicle’s VIN before it ships. This ensures that it communicates perfectly with your HHR’s Engine Control Module (ECM) and other systems right out of the box. You save hundreds of dollars and the headache of scheduling a visit to the dealer, making this an ideal fix for both professional mechanics and DIY enthusiasts.
Is Your HHR Showing These Transmission Problems?
- ✔ Harsh, erratic, or delayed gear shifts.
- ✔ Vehicle is stuck in “limp mode” (usually 2nd or 3rd gear).
- ✔ Check Engine Light or Transmission Warning Light is on.
- ✔ Diagnostic Trouble Codes (DTCs) are present, such as the general P0700 code or specific solenoid codes (e.g., P0750, P0751, P0752).
- ✔ The transmission refuses to upshift or downshift correctly.
- ✔ A noticeable decrease in fuel economy.
- ✔ Intermittent loss of communication with the transmission module.
A Straightforward Guide to Installation
For the 2006-2011 HHR, this is a repair you can confidently do at home. The entire process typically takes less than 30 minutes with basic tools.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before starting any electrical work.
- Locate the Module: On the Chevy HHR, the TCM is conveniently located in the left-hand (driver’s side) engine compartment. It’s a silver box with electrical connectors.
- Swap the Part: Carefully unplug the wiring harness connectors. Then, unbolt the old module from its mounting bracket. Install the new module in its place and securely re-attach the harness connectors.
- Final Steps: Reconnect the battery terminal. While the module is plug-and-play, it’s always a good practice to use a basic OBD2 scan tool to clear any stored fault codes from the vehicle’s memory.
Verified Vehicle Compatibility
This T42 TCM, including part number YNXS, is a direct replacement for a wide range of General Motors vehicles. While this page focuses on the HHR, it also fits many other popular models. Always confirm your part number or contact us with your VIN to ensure perfect fitment.
- Chevrolet HHR (2006-2011) – Transmission; (LH engine compartment)
- Chevrolet Cobalt (2006-2010) – Transmission; (LH strut tower)
- Pontiac G5/G6 (2006-2010) – Transmission; (LH strut tower)
- Saturn Ion (2006-2007) – Transmission; (behind LH strut tower)
- And many other GM cars, trucks, and SUVs from 2006-2014.
What does ‘VIN Programmed’ actually mean for me?
What does ‘VIN Programmed’ actually mean for me?
It means you don’t have to take your vehicle to a dealership for expensive programming. We load your car’s specific Vehicle Identification Number (VIN) and the latest GM software onto the module before we ship it. It arrives ready to install and function correctly, saving you time and money.
Is this module difficult to install on my 2008 HHR?
No, it’s one of the easier module replacements. For the HHR, the TCM is located in the driver’s side of the engine compartment. With basic hand tools, most people can swap it out in under 30 minutes.
Will this 2006-2011 HHR Transmission Module fix a P0700 code?
Yes, a faulty TCM is a very common cause of a P0700 trouble code. This code is a general fault request from the TCM to the main engine computer. Replacing a failing TCM often resolves the P0700 code along with any other specific transmission codes that were present.
Do I need to send my old part back? Is there a core charge?
No. We do not require a core return for this part. You can keep your old module, which simplifies the process for you.
What if the part number on my old module is different from YNXS?
This T42 module is interchangeable with many different GM service numbers. Part number YNXS is one of many compatible numbers. Please check the full interchange list on our product page or provide us with your VIN, and we will guarantee you receive the correct, compatible part for your HHR.