Drive Unit Motor and Inverter Over Temperature
The TESLA-DI_A116 (Tesla DI (Drive Inverter) Controller) EV fault code means: Drive Unit Motor and Inverter Over Temperature. This is a serious severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- moderate
- Estimated cost
- $0-$150 DIY for coolant flush and refill or hose replacement. Pro diagnosis at an independent EV shop runs $100-$200 for a coolant system inspection. Drive unit replacement if internals are damaged runs $3,000-$8,000 depending on model and whether the unit is remanufactured.
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Common Symptoms
- Touchscreen displays a yellow warning about reduced power or motor temperature
- Acceleration feels noticeably weak or sluggish compared to normal
- Car enters a reduced-power limp state and will not accelerate hard even with full pedal
- DI_a116 appears in the fault log via Scan My Tesla app with an OBDLink MX+ or Veepeak adapter
- Power meter on the energy display shows a hard ceiling well below the vehicle's rated output
- Fault often clears on its own after 15-30 minutes of gentle driving or parking with climate on
- In severe cases the car may coast to a stop and refuse to accelerate until temperatures drop
Probable Causes (Ranked by Likelihood)
- Sustained high-load driving such as track lapping, repeated full-throttle launches, or long steep hill climbs exhausting the drive unit's thermal headroom Very Likely
- Hot ambient temperatures combined with moderate spirited driving tipping the drive unit over its thermal threshold faster than normal Very Likely
- Drive unit coolant flow restricted by a clogged coolant strainer, degraded coolant, or a partially failed coolant pump reducing heat rejection from the inverter and stator Likely
- Air pocket or low coolant level in the thermal loop causing inconsistent cooling of the power electronics Likely
- Drive unit coolant temperature sensor fault causing the DI controller to read falsely high temperatures and derate prematurely Possible
- Software or firmware bug in the DI controller misinterpreting thermal sensor data, particularly on older firmware versions with known thermal model issues Possible
- Internal drive unit bearing or winding damage increasing friction and internal heat generation beyond normal levels Less Likely
Step-by-Step Diagnostic Procedure
Open the Tesla service menu by long-pressing the Tesla logo or navigating to Controls > Service. Check the Motor Temperature and Inverter Temperature fields to see live thermal readings at the time of the fault.
Connect Scan My Tesla app using an OBDLink MX+ or Veepeak adapter plugged into the OBD port under the dashboard. Pull the fault log and note the exact DI_a116 entry timestamp, plus any companion codes such as DI_a112 or DI_a117 that point to a specific thermal zone.
Review your recent drive pattern honestly. If you were doing repeated 0-60 launches, track lapping, or climbing a long grade in summer heat, the fault is almost certainly thermal saturation from normal use and not a hardware failure. Allow 20-30 minutes of rest with climate control running to help cool the drive unit loop.
Check the 12V coolant reservoir for the drive unit thermal loop (location varies by model, consult the frunk or front motor bay area depending on your variant). The fluid should be at or above the MIN line and appear clear or light green, not brown or cloudy. Low or discolored fluid points to a cooling system problem.
With the car OFF and cooled down, inspect coolant hoses running to the drive unit for soft spots, cracks, or evidence of weeping at clamp joints. A collapsed hose can restrict flow enough to cause thermal events under load.
If the fault recurs during normal non-track driving in mild weather, log the coolant pump activity via Scan My Tesla during your next drive. The coolant pump should ramp up proportionally with drive unit temperature. A pump that stays at a fixed low speed or does not respond is a failure candidate.
Measure coolant pump voltage at its connector if you have access. The pump should see 12V supply. A reading below 10V under load suggests a wiring or ground issue starving the pump.
If none of the above explain repeated faults during normal driving, the fault likely requires Tesla Toolbox 3 for a full drive unit thermal diagnostic log. At that point schedule a Tesla service center or a licensed independent EV repair shop visit, as internal drive unit diagnosis goes beyond DIY scope.
Frequently Asked Questions
What does Tesla code DI_a116 mean?
It means the drive unit, which combines the electric motor and the power inverter into one assembly, has exceeded its safe operating temperature. The car automatically reduces power output to protect the hardware. It is not a sign of permanent damage in most cases, just thermal saturation from hard use.
Can I still drive with DI_a116 active?
Yes, but with significantly reduced power. The car will limp along and let you get home or to a safe stop, but you will not have normal acceleration. Do not try to push through the derate by flooring it. That will not override the protection and could extend the cool-down period.
How much does it cost to fix DI_a116?
If the fault is caused by normal track or hard driving, it costs nothing. Just let the car cool down. If the cooling system needs a flush and refill, budget $50-$150 DIY or $150-$300 at a shop. A full drive unit replacement, which is rarely needed for this code alone, runs $3,000-$8,000 depending on the model.
Will the fault clear on its own?
Usually yes. Park the car with the climate system running to keep the coolant pump active, and the fault typically clears in 15-30 minutes once drive unit temperatures drop back into the normal range. If it keeps returning during everyday driving and not just hard use, something in the cooling loop needs attention.