Is Your Chevy HHR Shifting Erratically? Let’s Get It Fixed.
If you’re dealing with a 2006-2011 Chevrolet HHR that’s struggling to shift, slamming into gear, or stuck in limp mode, you know how frustrating it can be. As a technician with over two decades in the bay, I’ve seen this exact scenario countless times. The culprit is often a failing Transmission Control Module (TCM). This small computer is the brain of your automatic transmission, and when it starts to malfunction, it can cause a host of problems that make your reliable HHR feel unpredictable and unsafe. Don’t let a faulty module sideline your vehicle. This direct-replacement T42 TCM, part number 24240449, is the solution you need.
We take the guesswork and dealership hassle out of the repair. Each module is professionally programmed to your vehicle’s specific VIN before it ships. This means no expensive trips to the dealer for programming—it arrives ready for a true plug-and-play installation. It’s designed to restore the precise, smooth shifting your HHR had from the factory, improve fuel economy, and clear those persistent transmission-related trouble codes for good.
Case Study: A Tricky Diagnosis
A customer brought in their ’09 HHR with a weird issue: it would drive perfectly for 15 minutes, then suddenly refuse to shift out of 2nd gear, flashing a check engine light. After cooling down, it would work again. We checked the fluid and solenoids—all fine. The scan tool showed an intermittent P0750 code (Shift Solenoid A Malfunction), but the solenoid itself tested good. This pointed me straight to the TCM. Heat soak was causing an internal failure in the module, disrupting the signal to the solenoid. We installed one of our VIN-programmed T42 modules, and the problem was solved instantly. The customer saved hundreds in diagnostic fees and avoided replacing perfectly good transmission parts.
Diagnosing a Faulty 2006-2011 HHR Transmission Module
A failing TCM doesn’t always mean a complete transmission breakdown. Often, the signs are subtle at first and worsen over time. If your HHR is showing any of the symptoms below, it’s a strong indicator that the T42 module needs replacement. Addressing it early can prevent further damage to your transmission’s mechanical components.
Common Signs of a Failing TCM
- ✔ Harsh, delayed, or unpredictable gear shifts.
- ✔ The vehicle is stuck in a single gear (limp mode), often 2nd or 3rd.
- ✔ Check Engine Light or Transmission Warning Light is on with codes like P0700 or other solenoid-related DTCs.
- ✔ Failure to upshift or downshift, leading to poor acceleration.
- ✔ A noticeable drop in fuel efficiency.
- ✔ The transmission seems to slip between gears.
DIY Installation: A Straightforward Guide
For the Chevy HHR, replacing the TCM is a job most DIYers can handle in their driveway in under 30 minutes. It’s located in the engine compartment on the driver’s side, making it easily accessible.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and help reset the system.
- Locate the Module: Open the hood and find the TCM. In the 2006-2011 HHR, it’s typically mounted in the left-hand (driver’s side) engine compartment.
- Disconnect and Remove: Carefully unplug the electrical connectors from the old module. Press the release tabs firmly. Then, unbolt the module from its mounting bracket.
- Install the New Module: Bolt the new, pre-programmed TCM into place. Securely reconnect the electrical connectors, ensuring they click into place.
- Final Steps: Reconnect the negative battery terminal. Start the vehicle and let it idle for a few minutes. If you have a basic scan tool, use it to clear any stored fault codes. Take the vehicle for a test drive to confirm smooth shifting.
Verified Vehicle Compatibility
This T42 TCM is a direct fit for the 2006-2011 Chevrolet HHR and is also compatible with a wide range of other GM vehicles. It interchanges with part numbers including 24252114, 24234503, 24240449, and more. Please see the full list below to confirm your application.
This part will fit these makes and models with these options:
HHR 06-11 Transmission; (LH engine compartment)
COBALT 06-10 Transmission; (LH strut tower)
G5 07-10 Transmission; (LH strut tower)
IMPALA 06-11 Transmission; (lower air cleaner housing)
LACROSSE 06-09 Transmission; (lower air cleaner housing)
LUCERNE 06-11 Transmission; (LH engine compartment)
MALIBU 06-10 Transmission; (LH frame rail)
MONTE CARLO 06-07 Transmission; (lower air cleaner housing)
TAHOE 07-09 Transmission; (next to battery)
SILVERADO 1500 PICKUP 07-13 Transmission; (next to battery)
SAVANA 1500/2500/3500 VAN 06-14 Transmission; (RH engine compartment)
…and many more GM models. Please verify your part number for an exact match.
Frequently Asked Questions
Do I need to program this module?
No. This Transmission Control Module is delivered pre-programmed to your vehicle’s VIN. It is ready for installation right out of the box, saving you a trip to the dealership.
What tools are required for installation on an HHR?
You will only need basic hand tools. A socket set to remove the mounting bolts and a flathead screwdriver to help with the connector tabs are typically all that’s necessary. The entire job usually takes less than 30 minutes.
Is there a core charge for my old part?
No, there is no core charge. You can keep your old module without any extra fees or hassle, making the repair process simpler and more affordable.
Will this fix a P0700 trouble code?
A P0700 code is a generic fault code indicating the TCM has detected a problem. While this module often resolves the root cause (like a faulty solenoid circuit within the TCM itself), you should always diagnose any other specific codes that appear alongside it. In many cases, replacing a bad TCM will clear the P0700 code.
What is the warranty on this part?
This module comes with a one-year warranty, giving you peace of mind and confidence in the quality and reliability of your repair.