P2671 points to voltage on the second actuator supply when the controller has switched it off, so the line is fed from outside or the switch inside the module no longer opens. The solenoids on that supply can then no longer be de-energised as a group, which defeats the failsafe. GM tests this mostly at start-up or shut-down: in the 16OBDG08 TCM tables a short to power below 0.5 ohm is detected during initialisation with the driver off; the 2023 TCM checks at power-down whether the supply stays above 70 % of battery voltage, stores the result and sets the code at the next start as Type B. GM's hybrid HPC1 table of 2019 likewise rates it Type B. Ford's 2014 list contains P2671 without MIL. P2669 is the open circuit, P2670 the short to ground.
Medium severity. Can I keep driving?If the car is running normally, drive in moderation to a repair shop. If it loses power or another warning appears, do not continue.
Symptoms
- Warning lamp after the next start
- Often no immediate shift complaint
- Failsafe may not engage correctly if another fault occurs
Most likely causes
- Supply line shorted to another powered circuit
- High-side switch in the controller stuck closed
- Moisture or corrosion bridging pins in the transmission connector
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: hard
- It can trigger limp mode.
- It affects emissions.
What each character of P2671 means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- 6: Control modules and outputs
- 71: Specific fault in that system
Frequently asked questions
Can I keep driving with code P2671?
If the car is running normally, drive in moderation to a repair shop. If it loses power or another warning appears, do not continue.
What causes code P2671?
The most common causes are: supply line shorted to another powered circuit; high-side switch in the controller stuck closed; moisture or corrosion bridging pins in the transmission connector.
Related codes
- P2669Actuator Supply Voltage B Circuit/Open
- P2670Actuator Supply Voltage B Circuit Low
- P0659Actuator Supply Voltage A Circuit High
- P2686Actuator Supply Voltage C Circuit High
Sources
- gsi.ext.gm.com: 16OBDG08 Transmission Diagnostics
- gsi.ext.gm.com: 23OBDG07
- gsi.ext.gm.com: 19OBDG01 Hybrid Diagnostics
- performanceparts.ford.com: 2014 BOSS 302S OBDII Codes
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.