Mercedes-AMG
A45 / CLA45 W176 / C117 · 2013 – 2018
M133 2.0 turbo, valves pinned open. Bangs, pops and decel chatter from a stock back-box.
- Suits A45 AMG and CLA45 AMG W176/C117
- Single-module install behind the bumper
- Keyfob control with two-button toggle
- Reversible with no trace of install
Free UK shipping
2-year warranty
Fully reversible
The honest pitch
What this actually does to your A45 / CLA45
The M133 was, for a while, the most powerful production four-cylinder ever made. It also had a brilliantly antisocial exhaust note that Mercedes muted year on year via the valve programming.
Plug this in and the W176 sounds like the launch-spec car again. The decel snap-crackle that originally sold the AMG hot-hatch concept comes straight back.
Fitment
Mercedes-AMG A45 / CLA45 W176 / C117
Years
2013 – 2018
Install time
~10 minutes
Tools needed
None
Long read
The Mercedes-AMG A45 / CLA45 valve story
The W176 A45 AMG arrived in 2013 as, for a moment, the most powerful production four-cylinder ever made. It also arrived with an exhaust note that was deeply antisocial for a hot hatch — exactly what AMG buyers wanted. Subsequent firmware updates and emissions changes muted it. The 2017 facelift is noticeably quieter than the 2013 launch car despite the same engine and pipework. The valve programming did most of that.
Open Valve restores the launch-spec valve behaviour. The M133 then crackles and pops the way it did when the press first drove it. The decel snap on every gear change comes back hard.
Single actuator, single module. Install lives behind the rear bumper trim on the offside — fish the module in past the wheel-arch liner, no need to drop the bumper. About ten minutes.
Same kit and procedure works on the CLA45 AMG (C117) — same engine, same back-box layout, same actuator.
Install — step by step
- 01
Park with the rear of the car accessible. Boot open helps.
- 02
Lower the rear of the offside wheel-arch liner (three T20 torx).
- 03
Reach up to the valve actuator on the rear silencer. Disconnect the 2-pin connector.
- 04
Plug the module inline. Velcro module body to the chassis rail.
- 05
Refit liner.
- 06
Pair fob, test.
In the box
- One valve override module (one per actuator)
- Two-button RF key fob (CR2032 pre-installed, spare in the box)
- OEM-pattern connectors — no cutting, no splicing, no scotch-locks
- Printed install card with model-specific photos and a workshop QR link
Fitment notes
- ·W176 A45 AMG, C117 CLA45 AMG, X156 GLA45 AMG — all supported, same kit.
- ·Pre-facelift (2013–2015) and facelift (2016–2018) both supported.
- ·Original A250 / A220 / A180 W176 cars do not have a valved exhaust.
Mercedes-AMG A45 / CLA45 — FAQ
Does it work on the CLA45?+
Yes. The CLA45 (C117) shares the W176's M133 engine and exhaust hardware. Same single-module kit.
What about the GLA45?+
Yes — same kit. GLA45 X156 uses the same actuator and connector.
Will it throw a warning light on the dash?+
No. The module sits in the signal path between the ECU and the actuator motor. The ECU sees a normal actuator response back, so there's nothing to flag. We've shipped thousands of these and not had a single check-engine call linked to the module itself.
Is it reversible?+
Yes, fully. Unplug the module, plug the OEM connectors back into each other, refit the trim — about three minutes' work. There's no permanent change to the car, no part cut, nothing in the ECU. Dealer service visits, MOT, sale to a new owner — pull it out and it's like it was never fitted.
Does it work with an aftermarket exhaust?+
If the aftermarket back-box retains the OEM-pattern valve actuators (most do — Akrapovic, Milltek, IPE, Capristo all run the factory motors), yes. If the system is a straight-through with no valves, there's nothing for the module to override.
Will it set off the cabin sound symposer?+
No — the M133's cabin sound is RPM-derived and stays unchanged. The real exhaust note from outside is what gets louder.
Do I lose any of the AMG drive modes?+
No. The drive mode switch still selects between Comfort / Sport / Sport+ / Manual / Race — but they'll all sound like Race because the valve is held open in all of them.
Disclaimer
Open Valve modules are intended for off-road and motorsport use only. Please confirm your car has factory valve-actuated exhaust before ordering — if you're not sure, message us first. Professional installation recommended. Use at your own risk.
