COD Off disables cylinder deactivation (Cylinder on Demand, called ACT at Volkswagen) in the ECU software. The engine runs on all cylinders all the time: no switching into "half" mode and no faults or limitations tied to the system. For tuners: send us the original file and get a ready-to-flash file with corrected checksums, on average in 30–60 minutes.
How an engine shuts down some of its cylinders
At light load the ECU stops injecting fuel into some cylinders and keeps their valves closed so no energy is wasted pumping air through them. The pistons keep moving, just without doing work. The remaining cylinders take on more load, the throttle opens wider and pumping losses drop.
Audi and Volkswagen do it on the camshafts. Each camshaft carries sliding sleeves with two profiles: a working cam and a zero cam with no lift. An electromagnetic actuator in the cam cover pushes a metal pin into a spiral groove on the sleeve, and the turning shaft moves the sleeve sideways by a few millimetres. The rocker roller lands on the zero cam and the valve stops opening. The switch takes 9–31 ms, within half a turn of the camshaft.
American V8s (GM, Chrysler) and Honda do it differently: oil pressure from solenoids unlocks pins in the lifters or rocker arms, so they stop passing the cam motion on to the valve. The idea is the same: some cylinders sit idle while the load is low.
When the ECU switches to part-cylinder mode
Only inside a narrow window of engine speed and load, with the engine warm and a suitable gear selected. Each engine has its own window:
| Engine | What shuts down | When |
|---|---|---|
| 1.4 TSI ACT (CPTA 140 PS, CZEA 150 PS), at Audi 1.4 TFSI COD | cylinders 2 and 3 | about 1,500–4,000 rpm at 25–75 Nm |
| 1.5 TSI evo (DADA, DPCA), ACTplus on evo2 | cylinders 2 and 3 | low and medium load |
| Audi 4.0 TFSI V8 (S6, S7, S8) | 4 of 8 cylinders | 960–3,500 rpm, 25–40% of peak torque, 3rd gear and up, coolant above 30 °C |
| Mercedes-AMG V8 (SLK 55 AMG) | cylinders 2, 3, 5 and 8 | 800–3,600 rpm in Controlled Efficiency mode |
The fuel saving shows where the engine spends a long time at light load. The VW 1.4 TSI with ACT saves 0.4 l/100 km in the NEDC cycle and almost a litre at 50 km/h in 3rd or 4th gear. On the Audi S8 it is about 5% in the NEDC, about 12% at 80 km/h and about 7% at 130 km/h. The gain only appears if the mode lasts longer than three seconds, because every switch costs some fuel itself.
Why tuners switch COD off
- How it feels. In part-cylinder mode torsional vibration rises, the exhaust drones and the cabin gets noisier. Manufacturers fight this with active engine mounts and active noise cancellation, yet many drivers still feel the changeovers.
- Extra parts. Actuators, sliding sleeves, solenoids and switchable lifters can fail. The ECU then logs system faults, shows warnings and may limit the engine.
- Known cases. In 2013 Honda settled a class action covering 1.6 million V6 vehicles with its second-generation cylinder deactivation. Owners complained of oil consumption of up to a quart per 1,000 miles and spark plugs that needed replacing as early as 24,000 miles. The warranty was extended by eight years.
What COD Off changes
The software no longer allows the switch to part-cylinder mode. The ECU never issues the deactivation command: the actuators stay idle, every cylinder gets fuel and the mechanism stays on the working cams.
Goes away
- changeovers into part-cylinder mode
- faults and limitations tied to the deactivation system
- the drone and vibration of that mode
Stays as before
- all cylinders firing at any load
- the rest of the engine calibration
- starting, idle and acceleration
Light-load consumption goes up by whatever the system used to save. Under acceleration nothing changes, because at higher load the engine already runs on all cylinders. Checksums are recalculated, so the file is ready to flash straight away. Stage 1 can go into the same order.
What to check in the workshop
- If the car arrives with a mechanism fault, first find out what position the mechanism is in. Software cannot move a sleeve that is stuck on the zero cam, and that cylinder will stay without valves. That is a repair job.
- After flashing, clear faults and drive at light load inside the window where the system used to switch. There should be no misfires. If the car used to show the mode on the dashboard (Audi does), that indication will no longer appear.
- Faults unrelated to cylinder deactivation stay where they are. If the customer needs a specific code removed, add DTC Off to the order.
How to order the file
There is no ready-made ECU list for COD Off on the site. Send the file with a request and we will check whether there is a solution for your ECU.
- Read the original file via OBD or on the bench; pinouts are in the ECU pinout section. We need an unmodified stock file.
- Upload it to the portal, select COD OFF and tell us the engine and the reason: mechanism faults, vibration, tuning.
- Wait for our reply. If there is a solution for the ECU, the finished file with recalculated checksums arrives on average within 30–60 minutes.
- Flash the file, clear faults and check the engine at light load.
Keep the original: to bring the system back, just flash the stock file.
Send the file with a COD OFF request and we will check whether there is a solution for your ECU. If there is, the finished file arrives on average in 30–60 minutes.
Order COD OffFrequently asked questions
What are COD and ACT?
Systems that shut down some cylinders at light load by cutting injection and keeping their valves closed. COD is Audi's name and ACT is Volkswagen's; on the 1.4 TSI it is the same system.
What changes after COD Off?
The engine runs on all cylinders all the time: the changeovers into half mode, the faults tied to it, the drone and the vibration go away. The rest of the calibration is unchanged.
Will fuel consumption go up?
At light load, yes, by whatever the system used to save. On the VW 1.4 TSI that is 0.4 l/100 km in the NEDC and almost a litre at 50 km/h in 3rd or 4th gear.
Will the software fix a faulty mechanism?
No. If a sleeve or lifter is stuck in the deactivated position, that cylinder stays without valves, which is a repair job. The software only stops issuing the deactivation command.
Can the system be restored?
Yes, by flashing the original file, as long as the mechanism works. Always keep the stock file.
Is there a solution for my ECU?
There is no ready-made list. Send the file with a request and name the engine: we will check the software and reply.
Can COD Off be combined with Stage 1?
Yes, in one file and one order, provided there is a solution for the ECU.
How long does the file take?
If there is a solution for the ECU, on average 30–60 minutes.