Your Aston Martin DBS or DB9 suddenly drops into limp mode. The throttle response feels like you’re pushing through wet concrete. The check engine light is on, and your scanner shows P2106 – Throttle Actuator Control System – Forced Limited Power.
Most people immediately blame the throttle body.
Sometimes they’re right. But on modern Aston Martins – especially V12 cars with dual ECUs – P2106 can be a symptom, not the root cause.
In this article we’ll break down:
What P2106 actually means
Common mechanical causes you should rule out
When to suspect deeper ECU or immobilizer issues
How UpFix helps shops and owners get these cars out of limp mode for good
P2106 is a “torque management” or “limp mode” code. In plain English, it says:
“The engine computer detected a serious problem and is intentionally limiting power.”
On Ford-based platforms (including many Aston Martins), it can be set because of:
Throttle actuator faults
Throttle position sensor disagreement
Airflow or torque errors
Certain transmission or driveline faults
Severe misfires or fuel issues
Security / immobilizer problems that make the ECU cut power
In other words, P2106 tells you the ECU has pulled the plug, not why.
Before you dive into ECU diagnostics, you should always check the basics. On a DBS or DB9 with P2106:
Inspect both throttle bodies
Check for carbon buildup, sticking plates, or physical damage
Verify connectors and wiring for corrosion or broken pins
Check for related throttle codes
Codes like P2101, P2110, P2112, P2118 etc. can point to direct throttle actuator or position sensor faults.
Look at live data
Do commanded and actual throttle angles match?
Do pedal position sensors 1 & 2 agree with each other?
Check coils, plugs and misfire counters
Severe misfires can cause the ECU to limit power.
Inspect PCV and basic air path
Vacuum leaks and crankcase ventilation issues can cause strange airflow readings.
If all of that checks out – or you’ve already thrown parts at those areas without success – it’s time to think like an ECU.
On V12 Aston models with dual ECUs, P2106 often shows up as part of a larger pattern, not as a single isolated issue.
Here are red flags that suggest a control-module problem:
If you have:
One exhaust that gets hot
The other exhaust staying cold or just warm
…and live data for Fuel System Status shows one bank at “0 – No Fuel” while the other behaves normally, that’s a strong clue that one ECU is not enabling fuel.
This is exactly what we saw in Sam’s 2011 Aston Martin DBS case. The left bank behaved normally; the right bank looked like fuel was shut off at the ECU level.
If swapping or disconnecting ECUs leads to “key mismatch”, “immobilizer active” or similar security errors, that’s another big hint.
It often means:
A previous shop replaced one ECU with a used unit
The VIN and basic calibration were programmed, but
The immobilizer / key data wasn’t properly cloned
The car may start and run, but the security system isn’t fully happy. Under certain conditions, it can:
Command limp mode (P2106)
Disable fuel on one bank
Randomly refuse to start
Any time you see:
Tape or marker writing on an ECU case
Part numbers that don’t quite match the other side
Service records mentioning “reflash” or “cloned ECU”
…you should treat a P2106 limp mode complaint as partly an electronic/data problem, not just a hardware problem.
Many shops think: “If the VIN in the ECU matches the car, we’re good.”
On Ford-based Aston platforms, that’s only part of the story.
ECUs also store:
Immobilizer / security data
Key information
Checksums and other internal consistency values
If you program only the VIN and calibration into a used ECU but leave the security section mismatched, you’ve created a time bomb:
The car might start, but fuel can be cut later
Swapping ECUs side-to-side can trigger a “key mismatch” no-start
P2106 shows up as the ECU’s way of saying “I don’t trust this situation”
In Sam’s Aston Martin DBS case:
The car had P2106 and limp mode, with extremely slow throttle response
The right exhaust stayed cold, and live data showed no fuel on that bank
After swapping the ECUs, the car threw a key mismatch and wouldn’t start
When the modules arrived at UpFix:
Both ECUs communicated on the bench
Both showed the same VIN and calibration
But deep memory analysis revealed that the immobilizer blocks didn’t match
Someone had clearly tried to replace or clone an ECU in the past – they just didn’t finish the job.
We fixed it by cloning the correct immobilizer data from the good ECU to the replacement, turning them into a properly matched pair. Once reinstalled, the DBS could run both banks without limp mode, and P2106 disappeared.
If you’ve got an Aston Martin DBS or DB9 with P2106 and limp mode, work through this checklist:
Check and clean both throttle bodies
Mechanical movement
Connectors and wiring
Related throttle actuator codes
Verify coils, plugs and misfire status
Fix obvious misfires first.
Compare bank-to-bank behavior
Exhaust temperatures
Fuel system status per bank
Injector command and pulse width
Ask about ECU history
Any prior replacements?
Any non-factory programming or tuning?
Mismatched part numbers or labels?
If one bank is “no fuel” and immobilizer errors appear, stop guessing
At that point, you’re likely dealing with:
A failing ECU driver, or
A security/immobilizer mismatch between modules
That’s where UpFix can save you a lot of time and your customer a lot of money.
When you send ECUs to UpFix for an Aston Martin in limp mode:
We bench-test both ECUs (left and right)
Verify VIN, calibration and immobilizer data
Repair hardware faults where possible
Clone or correct immobilizer blocks so the modules agree and the car trusts them again
Provide tech notes you can reference on your RO or in your YouTube video
Instead of throwing more throttle bodies, coils or “good used” ECUs at the problem, you keep the original electronics in the car and fix the root cause.
You also help keep expensive modules out of the landfill – repairing and reusing electronics is almost always more sustainable than replacing them.
If you’re looking at:
An Aston Martin DBS or DB9
Limp mode with P2106
One bank cold, “no fuel” status
Key or immobilizer errors after an ECU swap
…it’s time to get the ECUs professionally tested and repaired.
📞 Call UpFix at 888-979-9343 or visit UpFix.com to start your repair.
Send in both ECUs, include a note with your scan data and symptoms, and we’ll let you know exactly what’s going on – so you can get the car out of limp mode and back on the road.