P0601 on 2013-2015 Buick Encore: Internal Memory Fault Causes and Fixes

What's Unique About the 2013-2015 Buick ENCORE

For this generation of Buick Encore and its platform mates (Chevy Trax, Cruze, Sonic), General Motors issued a specific Technical Service Bulletin (TSB #PIP4653E) that highlights the Transmission Control Module (TCM) as a known source for the P0601 code. This is important because while P0601 often points to the main engine computer (ECM), on the Encore it can just as easily be a transmission-related failure. This may present with shifting problems or a P0700 (Transmission Control System Malfunction) code alongside the P0601.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Check Engine Light is on
• Vehicle may not start or may be hard to start
• Engine may stall intermittently while driving, especially as it warms up
• Harsh or erratic transmission shifting
• Vehicle enters a reduced power "limp mode"
• ABS or Traction Control lights may illuminate
• Vehicle crawls forward slowly when put in Drive

Most Likely Causes

1. Internal Failure of the Engine Control Module (ECM/PCM) 🔴 High Probability → Shop Engine Control Module (ECM) Control modules can fail over time due to heat, vibration, and age, leading to internal short circuits or memory corruption on the circuit board.
   How to confirm: After confirming battery voltage and grounds are good, a professional scan tool is used to verify the P0601 code is logged by the ECM. An attempt to re-flash the software may be made; if the code returns immediately, the hardware is faulty and the module must be replaced.
   Typical fix: Replace the Engine Control Module and program the new unit to the vehicle.
   Est. part cost: $300-$800
2. Internal Failure of the Transmission Control Module (TCM) 🔴 High Probability → Shop Transmission Assembly GM TSB #PIP4653E specifically identifies the TCM as a common source of P0601 on the 2013-2014 Encore and its platform mates. These modules, often located inside the transmission, are subjected to heat, vibration, and potentially contaminated fluid, leading to failure.
   How to confirm: Use a professional scan tool (like the GM Tech 2 or GDS2) to confirm that the P0601 code is specifically stored in the TCM, not the ECM. The presence of code P0700 alongside P0601 is a strong indicator the fault lies with the TCM.
   Typical fix: Replace the Transmission Control Module and program the new unit. 🎬 Watch: Professional programming of a new GM transmission control module. On these vehicles, the TCM is often integrated with the valve body. 🎬 See how to clone and program a used TCM module.
   Est. part cost: $250-$700
3. Low or Unstable Battery Voltage ⚪ Low Probability → Shop Vehicle Battery Voltage spikes or drops from a weak battery, failing alternator, or poor connections can corrupt a module's memory during startup or shutdown. This is a common trigger for false P0601 codes across many vehicles.
   How to confirm: Test the battery with the engine off (should be >12.4V) and the charging system with the engine running (should be 13.5V-14.5V). Crucially, inspect and clean battery terminals and main ground straps (battery-to-chassis, engine block-to-firewall) for corrosion and tightness, as a bad ground is a known cause of module failure.
   Typical fix: Replace the weak battery, faulty alternator, or clean/repair battery and ground connections.
   Est. part cost: $150-$500

Rare But Worth Checking

• Failed Aftermarket Engine/Transmission Tune: → Shop Transmission Assembly If the vehicle was recently programmed with non-OEM software, a bug or improper flash can corrupt the module's memory and trigger a P0601 code.
• Water Intrusion: If water leaks into the cabin or engine bay and reaches the ECM or its connectors, it can cause short circuits and permanent damage to the module.

Diagnosis Steps

1. Verify Battery and Charging System Health: Use a multimeter to test the battery voltage (should be above 12.4V engine off) and alternator output (should be 13.5-14.5V engine running). Clean any corrosion from battery terminals.
2. Inspect Power and Ground Connections: Check the main power and ground connections to the ECM and TCM. Ensure they are clean, tight, and free of corrosion. Pay special attention to the main battery-to-chassis ground and engine-to-chassis ground straps.
3. Scan for Codes in All Modules: Use a professional-grade scan tool to read codes from all vehicle modules. Crucially, determine if the P0601 code is stored in the Engine Control Module (ECM) or the Transmission Control Module (TCM). This is the most important diagnostic step.
4. Attempt to Clear Codes: Clear the DTCs and cycle the ignition. If P0601 returns immediately, it indicates a hard internal fault.
5. Attempt Software Reflash (Professional Only): Per TSB #PIP4653E, if the code is in the TCM, the first step is to attempt reprogramming it with the latest GM software. If the reflash fails or the code returns, the module is condemned.
6. Replace the Faulty Module: If all external factors are ruled out, the identified control module (ECM or TCM) has failed and must be replaced and programmed.

Parts You'll Likely Need

• Engine Control Module (ECM/PCM) (OEM #12669329) — This is the most common cause of P0601 when the code is logged by the engine computer. It is the 'brain' of the engine and an internal failure requires replacement.
  Trusted brands: ACDelco, Bosch, Cardone
  OEM price range: $400-$800
  Aftermarket price range: $300-$500
• Transmission Control Module (TCM) (OEM #24286709) — A known issue for this vehicle, as cited by GM TSB #PIP4653E. If diagnostic scans point to the TCM, it must be replaced. This part is often sold as a combined unit with the valve body.
  Trusted brands: ACDelco, Dorman
  OEM price range: $350-$700
  Aftermarket price range: $250-$450

Related Codes That Often Appear With This One

• P0700 — Transmission Control System Malfunction. This code is often set in the ECM when the TCM detects a fault and requests the Check Engine Light. Seeing P0700 and P0601 together strongly points to the TCM being the source of the problem.
• P0603 — Internal Control Module Keep Alive Memory (KAM) Error. This code is part of the same family of internal module faults and is mentioned in TSB #PIP4653E alongside P0601.
• P0604 — Internal Control Module Random Access Memory (RAM) Error. Also part of the internal module fault family and cited in TSB #PIP4653E.
• P1621 — Control Module Long Term Memory Performance. This is another GM-specific code related to module memory integrity, also mentioned in TSB #PIP4653E.

Technical Service Bulletins (TSBs) & Recalls

• PIP4653E: Mentions that DTC P0601 can be stored in the Transmission Control Module (TCM), causing a Malfunction Indicator Lamp. Instructs technicians to verify the fault location and attempt a reprogram if the TCM is the source.
• 05-06-04-060A: An informational bulletin grouping P0601 with other control module diagnostic codes.

Platform-Specific Known Issues

• TSB #PIP4653E notes that on 2013-2014 Buick Encores, DTCs P0601, P0603, P0604, P062F or P1621 can be stored in the Transmission Control Module (TCM), causing a check engine light. The bulletin advises technicians to verify which module set the code and, if it's only the TCM, to attempt a reprogram before replacement.
• TSB #05-06-04-060A is an informational bulletin that groups P0601 with several other control module DTCs, indicating it's a known family of faults across multiple GM modules.

Mechanic-Grade Diagnostic Values

• Ground Strap Resistance — expected: < 0.1 Ω. Failure: A reading higher than 0.1 Ω indicates a poor ground connection that can cause voltage irregularities and trigger a P0601.
• Voltage Drop Test (Power or Ground Side) — expected: < 0.5 V. Failure: A voltage drop greater than 0.5 volts under load points to excessive resistance in the circuit, which should be investigated before condemning the module.
• Charging System Voltage (Engine Running) — expected: 13.5V - 14.5V. Failure: Voltage outside this range indicates a problem with the alternator or battery that can cause module memory corruption.

Scan Tool Commands That Help

• GDS2 (GM Global Diagnostic System 2): SPS (Service Programming System) — Per TSB #PIP4653E, this is the required function to reprogram the TCM with the latest software. This should be attempted before replacing the TCM, as a software update may resolve the P0601 fault.
• Tech 2 / GDS2: Module Communication Test / Request Live Data — To verify that the scan tool can communicate with the suspect module (ECM or TCM). If the module does not respond or sends corrupted data, it helps confirm an internal module failure.

Wiring & Ground Locations

• G101 — Close to the starter motor, on the engine block.. This is a primary engine ground. A poor connection here can disrupt the ground reference for the ECM and TCM, causing unpredictable electrical faults like P0601.
• G107 — On the chassis, near the A/C accumulator in the engine bay.. This is the main chassis ground point that connects the engine ground (G101) to the rest of the vehicle's body and ultimately the battery. Corrosion or looseness here is a critical failure point.
• Engine-to-Firewall Ground Strap — A braided strap typically running from the rear of the engine/cylinder head to the vehicle's firewall.. This strap provides a redundant and critical ground path for the engine and its components. These are known to corrode or break, leading to intermittent electrical issues, including module faults.
• TCM Main Connector — On the side of the transmission where the main vehicle harness connects. On a 6T40/6T45, this is a 14-pin connector.. This is the single point of failure for all power, ground, and data signals to the TCM. Inspecting for bent pins, corrosion, or backed-out terminals is a crucial step before replacing the module.

Real Owner Repair Stories

• YouTube - "2011 GM Truck Stalling And P0601" (2011 Chevrolet Silverado (Similar GM electrical architecture)) — Vehicle would cut out while driving, setting P0601, ABS, and Service Stabilitrac messages.
  ❌ Tried (didn't work) Clearing the code (it would return when wiggling wires near the ground).
  ✅ What actually fixed it The technician found a corroded ground connection behind the power steering line near the motor mount. After cleaning the connection point and relocating the ground to a clean spot on a bracket, the P0601 code did not return.

OEM Part Supersession History

• 24265367, 24275318 → 24286709 — Standard part revision and consolidation for the 6T40/6T45 Gen 2 TCM.
  Heads up: The replacement TCM must be programmed to the vehicle's VIN using GM's Service Programming System (SPS) to function.
• N/A → 12669329 (Service Number 12668866) — This is a common service part number for the E78 ECM used in the 1.4L LUV engine.
  Heads up: A replacement ECM must be programmed to the vehicle's VIN. Some vendors offer a 'Clear Security' option that may simplify the key relearn procedure, but programming is still required for full functionality.

Model Year Variations Within This Range

• 2013-2015: TSB #PIP4653E specifies that for diagnosing the TCM, a Tech 2 scan tool may be used on earlier models, but 2013 and newer models like the Encore will require the use of GDS2 (GM's modern diagnostic software) to properly identify and reprogram the module.