Citroen C4 Inertia Switch Location & Reset (2004-2020)
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Citroën C4 fuel cut-off switch (coupe-circuit) location: Passenger-side footwell on C4 Mk1 (2004–2010). Behind the glove box on C4 Mk2 / DS4 (2010–2018). C4 III (2020+) and e-C4 use ECU-controlled crash cut — no mechanical switch.
Reset: Press the red plunger until it clicks flush. Turn ignition ON for 10 seconds, then start.
The Citroën C4 has gone through three quite different generations, and the inertia switch location moved accordingly. Owners of older C4s regularly trip the switch on French/UK underground car park ramps and speed bumps — here is where to find it on every C4 variant including the C4 Picasso / Grand Picasso MPV siblings.
In this guide:
What the Citroen C4 Inertia Switch Does
The inertia switch (PSA workshop name: coupe-circuit de pompe à carburant) is a mechanical cut-out between the ignition supply and the fuel pump. A weighted ball inside the sealed housing is held in a magnetic detent; sudden deceleration — crash, kerb strike, hard pothole — dislodges the ball and breaks the circuit. Engine runs for 2–3 seconds on rail pressure, then shuts down. It is a passive crash-protection feature preventing fuel spray from ruptured lines.
Citroën and Peugeot (both PSA / Stellantis brands) share the same inertia switch across nearly their entire range including the C3, C4, C4 Picasso, Berlingo, Peugeot 206/207/307/308, and Partner. The C4 uses the same switch part as the C3 — just in a slightly different physical location. For the cross-make overview, see our master fuel cut-off switch guide for 20+ makes.
Location by Generation
| Generation | Years | Location |
| C4 Mk1 (LC) | 2004–2010 | Passenger footwell, under the carpet near the firewall. Fold carpet back from door sill |
| C4 Mk1 Coupé | 2004–2010 | Same as Mk1 hatch — passenger footwell |
| C4 Mk2 (B7) | 2010–2018 | Behind the passenger-side glove box. Drop glove box by squeezing sides inward |
| C4 Mk2 facelift / Cactus | 2015–2018 (C4) / 2014–2020 (Cactus) | Same as Mk2 — behind glove box |
| C4 Picasso / Grand Picasso Mk1 | 2006–2013 | Passenger footwell, under carpet (shares platform with C4 Mk1) |
| C4 Picasso / Grand Picasso Mk2 | 2013–2022 | Behind the passenger-side glove box |
| C4 III (B72) | 2020+ | No mechanical switch — ECU-controlled crash cut |
| ë-C4 (BEV) | 2020+ | No fuel system — BMS handles crash cut |
| DS4 Mk1 (shares C4 Mk2 platform) | 2011–2015 | Behind the passenger-side glove box — identical to C4 Mk2 |
C4 Mk1 — Passenger Footwell
Open the passenger door. Slide the seat all the way back. Fold the carpet back from the door sill toward the centre of the car, exposing the footwell floor pan. The switch is a small black cylinder mounted on the floor pan or low on the firewall, red plunger on top. On some C4 Mk1 Coupé variants the sound-deadening underlay covers the switch — carefully peel it back (it is glued in places).
C4 Mk2 — Behind the Glove Box
Empty the glove box. Squeeze the side walls inward to release the stops and let the box swing down. The switch sits on the firewall, upper-right on LHD cars (upper-left on UK RHD). Red plunger facing up. On some C4 Grand Picasso Mk2 variants with the panoramic roof, there may be an additional trim piece above the glove box — prise it off gently to reach fully.
Step-by-Step Reset
- Turn ignition OFF. Remove the key (or foot off brake for keyless).
- Access the switch per the location guide above.
- Press the red plunger straight down firmly until it clicks and sits flush. Single firm press.
- Turn ignition to position II (ON, not start). Listen for the fuel pump prime — 2-second whirr from rear.
- Wait 10 seconds for rail pressure.
- Start the engine. Should fire within 1–3 cranks.
Why It Trips Without a Crash
- Underground car park ramps taken fast — particularly common in French and UK urban areas
- Hard potholes at motorway speeds
- Kerb strikes while parking
- Speed bumps on stiffer C4 VTR / VTS trims
- Dropping off a jack during a tyre change
- Age and internal magnet fatigue — older C4 Mk1 switches trip more easily past 150,000 km
Still Won't Start After Reset
- Fuel pump fuse. C4 Mk1: fuse F17 (15A) in dashboard fusebox. C4 Mk2: fuse F32 (15A) in engine-bay fusebox.
- Fuel pump relay. Swap with an identical relay from horn or A/C slot (~€10 replacement).
- Battery. Below 10V during cranking, the ECU will not enable the pump.
- 1.6 HDi / 1.6 BlueHDi diesel: known issues with fuel-rail pressure sensor past 150,000 km.
- 1.6 THP petrol: crank position sensor is a common C4 failure past 120,000 km.
Frequently Asked Questions
Where is the fuel cut-off switch on a 2008 Citroen C4?
Passenger footwell, under the carpet near the firewall. The 2008 C4 is Mk1 — fold back the passenger carpet from the door sill to expose the switch mounted low on the floor pan.
Does the 2013 Citroen C4 have a different switch location?
Yes. The 2013 C4 is Mk2 (B7) — the switch relocated to behind the passenger-side glove box. Drop the glove box by squeezing the sides inward.
Does the Citroen C4 Picasso share the same switch location?
Yes. C4 Picasso / Grand Picasso Mk1 (2006–2013) shares the C4 Mk1 platform → passenger footwell. Mk2 Picasso (2013+) shares C4 Mk2 platform → behind glove box.
Does the DS4 have an inertia switch?
The original DS4 Mk1 (2011–2015, when DS was still a Citroën trim) shares the C4 Mk2 platform — same switch behind the passenger glove box. The newer DS 4 (2021+, now its own brand) uses ECU-controlled crash cut with no mechanical switch.
My 2021 Citroen C4 does not have a physical switch — is that right?
Correct. The 2020+ Mk3 C4 uses ECU-controlled crash cut via airbag signal on all trims. If your new C4 will not start after an incident, the fault must be cleared with a scan tool at a dealer.
Is the C4 inertia switch the same part as the C3?
Electrically yes, the underlying component is identical. Mounting bracket may differ slightly by model year. For the C3-specific guide see our Citroen C3 inertia switch article.
