Citroën C3 Inertia Switch Location & Reset Guide (All Generations)
Drashco
Citroën C3 fuel cut-off (inertia) switch location: Passenger footwell on C3 I (2002–2009); passenger footwell or behind glove box on C3 II (2009–2016); behind the glove box on C3 III (2016+).
Reset: Press the red plunger until it clicks flush. Turn ignition ON for 10 seconds, then start.
The Citroën C3 shares its PSA Group (now Stellantis) architecture with the Peugeot 207, 208, and 2008 — which means the fuel inertia switch layout is nearly identical across these cars. If your C3 has a no fuel pump prime after a minor jolt, the inertia switch is a 30-second, zero-cost fix.
In this guide:
What the C3 Inertia Switch Does
The inertia switch is an in-line mechanical interrupter for the fuel pump's positive supply. Under normal conditions, a weighted ball sits in a magnetic detent. During a sudden deceleration — crash, pothole, kerb strike — the ball breaks free and opens the circuit, killing the fuel pump. The engine runs out of fuel pressure within seconds and shuts down.
The PSA-platform cars (Citroën C3, Peugeot 207/208, DS3) use the same switch supplier, so the symptoms, reset method, and failure modes are consistent across the family. For the cross-brand picture, see our master fuel cut-off switch guide.
Location by C3 Generation
| Generation | Years | Location |
| C3 I (A8) | 2002–2009 | Passenger footwell, under the carpet, near the firewall. Fold the carpet forward from the door sill to expose |
| C3 II (A51) | 2009–2016 | Early (2009–2012): passenger footwell. Later (2013–2016): some moved to behind the glove box — check both locations |
| C3 III (A55 / R51) | 2016–2024 | Behind the passenger-side glove box. Drop the glove box (three Torx T20 screws + two side clips) to access the firewall-mounted switch |
| C3 IV (C3 Aircross 2024+) | 2024+ | Same as Mk3 — glove-box firewall, shared layout with PSA "Smart Car" architecture |
| C3 ë-C3 (electric 2024+) | 2024+ | No fuel inertia switch — BEV with no fuel system |
C3 I / early C3 II — Footwell access
Slide the passenger seat all the way back. Get on your back with your head pointing toward the rear seats and your feet toward the A-pillar. Fold the carpet back from the door sill. You will see a mounting bracket holding a cylindrical black housing — approximately 6cm tall and 3cm in diameter — with a red or yellow plunger on top. That is the inertia switch. If the plunger is RAISED (proud of the housing surface), it is tripped. If FLUSH, it is not — and your no-start issue is something else.
C3 III — Behind the glove box
Open the glove box and empty it. Close the damper stopper arm on the right side. Squeeze both sides of the glove box toward the centre to release the side pegs from the dash, and let the whole box hang down. You will see the firewall behind. The inertia switch is mounted toward the upper-right, near the blower motor. It is connected by a two-wire white plastic connector. Plunger on top, facing up.
Step-by-Step Reset
- Turn ignition OFF, remove key.
- Access the switch per the location guide above.
- Press the plunger firmly straight down until it clicks and sits flush. One firm press — do not hammer it.
- Turn ignition to ON (position II). Listen for the fuel pump prime — a 2-second whirr from the rear of the car.
- Wait 10 seconds for the fuel rail to reach operating pressure.
- Start the engine. Should catch within 1–3 cranks.
Also Applies to: C3 Picasso, DS3, C3 Aircross
These closely-related PSA cars share the same inertia switch part and location:
- Citroën C3 Picasso (2008–2017): Passenger footwell, same as C3 I/II
- Citroën DS3 / DS 3 (2010–2019): Behind the glove box from 2010 onwards
- Citroën C3 Aircross I (2017–2023): Behind the glove box (shares dash with C3 III)
- Peugeot 208 I/II (2012+): Behind the glove box (for cross-reference when working with mixed-brand fleets)
- DS 3 Crossback (2019+): Behind the glove box
If you drive or service any of these, the same 30-second reset procedure applies.
Still Will Not Start After Reset
- Fuel pump fuse: C3 I = fuse F15 (20A) in the dashboard fusebox. C3 II/III = fuse F17 in the engine bay fusebox. A blown fuse points to a short in the pump or its wiring.
- Listen at the filler neck for the fuel pump prime when ignition is ON. No whirr = no power to pump. Check relay and fuse.
- Crankshaft position sensor: PSA platform CKP sensors are a common failure point on higher-mileage C3s. Symptom: cranks but never catches, no misfire codes initially. Cheap fix (£25 part, 30 minutes).
- Battery voltage: Small batteries in C3s can drop below the ECU's brown-out threshold during cranking, preventing fuel pump activation. If battery is over 4 years old and tests borderline, replace before chasing deeper issues.
- Diesel HDi models: Check the fuel primer bulb on the engine (mounted on the fuel filter housing on 1.4 HDi, 1.6 HDi). Pump it 20 times until firm — bleeding air out of the low-pressure side. If it stays soft, the prime pump or filter is suspect.
Frequently Asked Questions
Does the Citroën C3 Pluriel have the same inertia switch location?
The C3 Pluriel (2003–2010) shares the C3 I platform, so the switch is in the passenger footwell under the carpet, same as the standard C3 I hatchback.
Is there a fuel pump reset switch on the Citroën DS3?
Yes. Early DS3 (2010–2014) has it behind the glove box on LHD cars, under the driver's-side A-pillar carpet on some RHD UK cars (mirror-imaged dash). Later DS3 (2015–2019) universally behind the glove box.
Why does my Citroën C3 keep cutting out intermittently?
Most commonly on the C3: a loose main battery earth cable, a failing crankshaft position sensor, or a cracked throttle body plastic that is letting in unmetered air. Less commonly, the inertia switch is intermittently opening due to internal wear — particularly on C3s past 150,000 km. Scan for fault codes first; the switch is usually the last suspect.
Can the inertia switch cause the C3 to enter limp-home mode?
No. A tripped inertia switch kills the fuel pump entirely — the engine will crank but not start, or will shut off if tripped while running. Limp-home mode (reduced power, MIL on) is a separate powertrain fault triggered by the ECU, not the inertia switch.
Where is the inertia switch on a Citroën C3 Aircross SUV?
Behind the passenger-side glove box on all C3 Aircross I models (2017–2023) and the 2024+ C3 Aircross II. Same location, same part as the C3 III hatchback — drops the glove box, look at the firewall.
Is there an inertia switch on the new electric ë-C3?
No. The ë-C3 (from 2024) is a battery-electric vehicle with no fuel system, no fuel pump, and no mechanical inertia switch. Crash cut-off is handled entirely by the battery management system reading the airbag crash signal.
