Cluster showing the Pre-Collision System malfunction warning

Toyota Pre-Collision System (PCS) Fault: Why the Headlight Warning Often Comes With It

'Pre-Collision System Malfunction' on the dash of your Corolla, Yaris or RAV4, often with 'Headlight System Malfunction' beside it? Toyota Safety Sense reads the road through a forward camera on the windscreen glass and a millimetre-wave radar behind the grille or bumper, and the same camera runs the automatic high beam, which is why the two warnings tend to arrive together. Dynamic Radar Cruise Control leans on the same sensor pair, so it often drops at the same moment. The checks that cost nothing come first; calibration, when your car needs one, is from £162 inc VAT.

Please note

Safe to drive, but the auto-brake is off

You can drive the car. With PCS flagged, the automatic emergency braking side isn't watching the road for you, and whatever shares the faulted sensor usually drops with it: Dynamic Radar Cruise Control when it's the front radar, Lane Trace Assist and the automatic high beam when it's the windscreen camera. Normal brakes and steering are untouched. Leave more following distance and don't lean on the assists until it's sorted.

What's actually triggering PCS on your Toyota

Toyota Safety Sense reads the road through two sensors: a forward camera on the windscreen glass and a millimetre-wave radar behind the grille or bumper. Both feed the Pre-Collision System, the same pair runs Dynamic Radar Cruise Control and Lane Trace Assist, and the camera also handles the automatic high beam. That's why one disturbed sensor can fill the dash. The triggers, most common first.

The pairing that defines this fault on a Toyota. The forward camera on the windscreen glass feeds the Pre-Collision System and the camera-fed headlight logic from one image, so when its aim is off, both fail their self-check together. 'Pre-Collision System Malfunction' and 'Headlight System Malfunction' arriving at the same moment looks like two faults, but it's usually one cause, and one front camera calibration clears both.

The big trigger on the camera side. The camera comes off with the old glass and goes back on with the new, and its aim shifts by enough to fail the self-check even when the fitting is perfect. Many glass companies fit the screen and stop there, so the warnings appear on the drive home. The fix is a static aim on the forward camera to the documented Toyota procedure: front camera calibration, £162 inc VAT (£135 +VAT) at a centre.

The millimetre-wave radar sits behind the grille or bumper, right where the work happens; on the Yaris's 2024-on TSS 3 update it's mounted low behind the front bumper line. Unclipping and reclipping a bumper transfers enough force to shift the aim by a fraction of a degree, which is all the radar needs to flag, even when the bumper goes straight back on. PCS and Dynamic Radar Cruise Control both read from it, so a cruise warning often lands beside the PCS one. After a bigger front-end repair the camera can have moved too; both are checked, and calibrated where needed, in the same visit.

Trolley contact in a car park, a kerb strike on the lower bumper trim, a nudge that never left a mark. None of them show visible damage, but any of them can shift the radar bracket enough to throw the fault days later. A slow walk round the front end costs nothing and is worth doing before anything is booked.

A camera that can't see through road film or a misted patch of glass, or a radar face packed with snow, gets parked by the car until the view clears. That's a system limitation, not a fault, and there's nothing to calibrate and nothing to book: clean the camera's patch of windscreen and the grille zone, drive, and see if the warning stays gone. On the Auris, the 'screen needs cleaning' message often is this case in words, though it can also stay on when the glass is clean, which points at the aim instead. A warning that keeps returning on a clean car in clear weather is the aim, not the view.

The camera aim runs against a target board whose distance is set per model: the Prius camera sits higher in the glass than most, and the C-HR from 2023 uses the newer TSS 3 mount with its own aim reference. Calibrating against the wrong reference for your car's year is how an aim fails to hold. Send your registration when you enquire and the centre sets up for your exact Safety Sense generation.

If the trigger was a real impact, the camera bracket or the radar housing can be cracked rather than just shifted, and a calibration won't hold on damaged hardware. This is what the diagnostic scan is for: it says which case you're in before any work is booked, and if a sensor does need replacing, the rate card has a line for the calibration and coding that follow.

How we fix it

Worth checking first: note which warnings arrived together, because the pairing points at the sensor. PCS with the Headlight message is the windscreen camera; PCS with a cruise warning leans towards the front radar. Then the free checks: clean the camera's patch of glass and the grille zone, walk round the front end for signs of past work or a parking knock, and think about when it started. A warning that arrived in filthy weather can clear itself once the sensor can see. One that arrived with a windscreen swap or bodywork won't: the sensor moved with the work, and the car keeps flagging until the aim is reset.

Still showing? The job starts with a diagnostic scan, £54 inc VAT (£45 +VAT), always itemised as its own line. A PCS fault has more than one ending, a camera moved by a glass swap, a radar knocked off aim by bumper work, or hardware that's genuinely damaged, and the scan says which car you have before anything is booked.

From there it's one of three jobs:

  1. The camera's lost its aim. The usual outcome after a windscreen swap, and the one behind the PCS-and-Headlight pairing. It's a static aim against a target board set for your model and Safety Sense generation, to the documented Toyota procedure: front camera calibration, £162 inc VAT (£135 +VAT) at a centre.
  2. The radar's lost its aim. The normal outcome after bumper work or a knock. It's a static procedure against a separate radar target, and calibration runs to full manufacturer specification. Front radar calibration is £162 inc VAT (£135 +VAT); where both sensors moved, both are done in the same visit. Two or more systems in one visit: the highest-priced system is full price and each additional system is 35% off at a centre.
  3. A sensor was replaced. A new camera or radar needs coding to your car as well as the aim. On the rate card those are two lines, not one: coding for the replacement part first, then that system’s calibration, which takes the additional-system discount in the same visit. Front radar replaced: coding the new module is £232.80 inc VAT (£194 +VAT), with the front radar calibration following as its own line, discounted as an additional system. Front camera replaced: £229.20 inc VAT (£191 +VAT).

Every job closes with the paperwork. Certificate to manufacturer tolerances, the same standard dealers issue. Your quote is confirmed in writing before anything is booked. The procedure itself, step by step, is in our ADAS calibration guide.

Toyota calibration prices

One system is the usual quote here: the windscreen camera behind the PCS and Headlight pairing, or the front radar after bumper work. Rates are the same at every service centre, per system, shown inc VAT with the net figure alongside. Your total is confirmed in writing before anything is booked.

Calibration — per system

Service At a service centre
Front camera calibration £162 inc VAT (£135 +VAT)
Front radar calibration £162 inc VAT (£135 +VAT)
Blind spot radar calibration £162 inc VAT (£135 +VAT)
360° / surround camera calibration £162 inc VAT (£135 +VAT)
Reversing camera calibration £206.40 inc VAT (£172 +VAT)
Parking sensor calibration £184.80 inc VAT (£154 +VAT)

Coding a replaced part to your vehicle

Service At a service centre
Front radar replaced £232.80 inc VAT (£194 +VAT)
Front camera replaced £229.20 inc VAT (£191 +VAT)
Blind spot radar replaced £226.80 inc VAT (£189 +VAT)
Reversing camera replaced £213.60 inc VAT (£178 +VAT)
  • When your job needs a diagnostic pre-scan, it's £54 inc VAT (£45 +VAT), itemised separately. It reads available fault information; finding the cause may require further investigation. A post-scan is a separate operation.
  • Two or more systems in one visit: the highest-priced system is full price, each additional system is 35% off at a centre. Scans aren't part of the discount. Front camera and front radar together come to £267.30 inc VAT (£222.75 +VAT).
  • Replacement configuration and calibration are different operations. The work required depends on the vehicle and what the installer has already completed. Configuration prices do not include supplying or fitting a replacement part, or an automatic calibration bundle.
  • Unsuccessful work, further investigation or a return visit may carry charges, including at a service centre. The appointment terms and written quote set out the work and applicable charges before booking.
  • Mobile calibration is available for garages and bodyshops with workshop conditions. Ask us.

Get your Toyota's PCS calibration booked

Send your registration and a line on what's happened. We come back with the itemised quote, the nearest of 80+ UK service centres, and the soonest slot.

  • Per-system pricing, from £162 inc VAT.
  • Your quote is confirmed in writing before anything is booked.
  • Certificate to manufacturer tolerances, the same standard dealers issue.
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Frequently asked questions

Because they share the same camera. On a Toyota, the forward camera on the windscreen glass runs the Pre-Collision System and the camera-fed headlight logic from one image feed; on the Corolla that's been the layout since 2019. When the camera loses its aim, after a windscreen swap, a bumper repair or a low-speed front knock, the car can't reliably read the road for either job, so both warnings fail their self-check together. It looks like two faults but it's one cause, and one calibration usually clears both: front camera calibration is £162 inc VAT (£135 +VAT) in a centre visit.

It's priced per system, and which system depends on what set the warning off: the windscreen camera behind the PCS and Headlight pairing on most UK Toyotas, or the front radar when the trigger was bumper work, as on the Corolla and Yaris. Front camera calibration is £162 inc VAT (£135 +VAT), front radar is the same, with the full rate card on this page. Two or more systems in one visit: the highest-priced system is full price and each additional system is 35% off at a centre. A diagnostic scan, when your job needs one, is priced and itemised separately. Your quote is confirmed in writing before anything is booked.

Toyota Safety Sense (TSS) is the umbrella name for Toyota's driver assistance suite. The Pre-Collision System (PCS) is one feature inside it, the forward collision warning and automatic emergency braking side, alongside Dynamic Radar Cruise Control, Lane Trace Assist and the automatic high beam. The features share two sensors, the windscreen camera and the front radar, which is why a fault in one sensor often shows as warnings from several features at once. Whichever name your dash uses, the fix targets the sensor rather than the feature: re-aim the camera or the radar and the features that read from it come back together.

No. What the job needs is a calibration bay, the target references for your model's Safety Sense generation, and Toyota's documented calibration procedure, and our service centres run all three; nothing in it is franchise-only. Provided the work runs to Toyota's specification, an independent calibration doesn't invalidate your warranty under UK block exemption rules. Certificate to manufacturer tolerances, the same standard dealers issue. Dealer quotes for ADAS work run £300 to £900 in quotes customers have shown us.

It usually means the system is blocked, not broken. When the camera can't see through heavy rain, snow or road film, or the radar face is packed with snow, the car parks the Pre-Collision System until the view clears, and the message goes on its own. That's a designed limitation: there's nothing to calibrate and nothing to book. The free check is to clean the camera's patch of glass and the grille zone and see if the message stays gone. If 'PCS unavailable' or a PCS malfunction warning keeps returning on a clean car in clear weather, that's a lost aim rather than a blocked view, and a calibration is the fix: front camera or front radar, each £162 inc VAT (£135 +VAT) per system at a centre.

Usually the coding and the aim. A replacement camera or radar has to be coded to your car and then calibrated before the self-checks trust it, and fitting the part does neither on its own. The rate card carries a coding line per module, £232.80 inc VAT (£194 +VAT) for a replaced front radar and £229.20 inc VAT (£191 +VAT) for a replaced front camera, and that sensor's calibration is quoted as its own line at the second-system discount. Mention whether the unit was new or used when you enquire: a used module can be attempted, coding one isn't always possible, and the centre confirms the scope in writing before anything is booked.

Related ADAS warning guides

The two repairs behind most Toyota PCS faults each have a full cross-make guide. If your case started with glass or bodywork, the detail lives there.

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