2009-2021 Lotus Evora ABS Light On: Common Causes and Fixes

By Core Brake Parts Tech Team — Circleville, OH warehouse

On a 2009-2021 Lotus Evora, a lit ABS warning light most often points to the brake light switch at the top of the brake pedal, not to a failed ABS module. Lotus issued two service bulletins covering this exact symptom on Evoras fitted with the Bosch ABS/ESP module: one for fault code C0460 and one for fault code C0340. Read the stored code first, then work through the cheap checks before anyone quotes you a new module.

How the ABS System on the Evora Works

The Evora uses a servo-assisted, four-channel anti-lock system built around a Bosch hydraulic module, working with four-piston calipers at every corner. The ABS module decides when to release and reapply pressure at each wheel using three main inputs:

• Wheel speed sensors. Each hub carries an active sensor. Bosch describes these as Hall-effect sensors that read a rotating encoder ring and send digital pulses proportional to wheel speed to the ABS and stability control systems.
• A brake line pressure sensor. This sits inside the ABS module. Lotus states in bulletin 2013/04 that the pressure sensor is non-serviceable, meaning it is not replaced on its own.
• The brake light switch. On the Evora this is a two-stage switch. The first stage closes with light pedal effort and tells the car the driver is braking (it also cancels cruise control). The second stage closes with a little more pedal travel and turns on the brake lights.

The module constantly cross-checks these signals. If the brake lights come on when the module already sees more line pressure than it expects, or if the switch signal does not make sense, it stores a fault, disables ABS and lights the warning lamp. Normal braking stays available, but you lose anti-lock control and, on cars with stability control, usually that as well.

The Two Lotus Bulletins That Cover This Light

Both bulletins apply to Lotus Elise, Exige and Evora cars fitted with the Bosch module, and both point to the brake light switch before the expensive parts.

The important point in bulletin 2013/04 is its instruction: check and set the brake light switch first, before unnecessarily renewing the ABS module. Lotus only recommends looking at other causes if the light and the code come back after the switch has been checked and adjusted.

Symptoms and How to Diagnose Them

Symptoms you may notice alongside the ABS light:

• ABS and traction or stability lights on together, sometimes with a Service light.
• Cruise control that will not engage, or cancels on its own (a brake switch problem can cause this, which is why the bulletin also lists P0571).
• Brake lights that stay on, come on late, or flicker.
• A light that appears after a pedal box job, a footwell trim removal or anything that disturbed the switch.
• A light that is intermittent and clears after a restart, which fits a sticking plunger.

Diagnosis on this car needs a scan tool that can read the ABS module, not just a generic engine code reader. The dealer tool is Lotus TechCentre. In live data the bulletin has the technician watch the two switch stages alongside the ABS pressure sensor while pressing the pedal. With no pedal effort, both stages should read not actuated and pressure should sit near zero. With light pedal, stage one should actuate while pressure stays near zero. With a little more pedal, stage two should actuate as pressure rises into a low range (the bulletin gives 2 to 6 bar). If stage two only switches on after pressure has climbed past that, the switch timing is off and the module flags C0460.

If the code is not C0340 or C0460, the cause lies elsewhere: a wheel speed sensor code points to a sensor, its wiring or connector, or a damaged encoder ring at that corner. Low fluid in the reservoir can also trigger a brake warning, and low fluid on a car with healthy lines usually means worn pads.

Causes, Most Likely First

1. Brake light switch plunger out of adjustment. The plunger rides on an internal ratchet. If it was moved by hand while fitted, or set wrong after work in the footwell, the contact timing is off. Lotus warns that manually operating the plunger in place can trip the ratchet and change its length.
2. Sticking brake light switch plunger. The C0340 case. Lotus found lubrication cured switches that had been returned as failed.
3. Failed brake light switch. If the stages cannot be made to read correctly in live data, the bulletin says to replace the switch, check the new one, then set it.
4. Wheel speed sensor, wiring or connector. Look for road damage, a chafed harness or a corroded plug at the corner the code names.
5. Low brake fluid or a hydraulic problem. A separate Lotus bulletin from October 2013 asks technicians to check that every brake hose and pipe is routed so it cannot contact other components. A rubbed line is worth ruling out on any Evora with a fluid or warning light complaint.
6. ABS module fault. Last on the list. The internal pressure sensor is part of the module, so a genuine sensor failure means a module, but only after the switch checks above.

The Fix: Setting the Brake Light Switch

This is a short job, which is why Lotus lists it first. In outline, from bulletin 2013/04:

1. From the driver's footwell, turn the switch a quarter turn counter-clockwise and pull it from its bracket with the connector still attached.
2. Push the plunger fully in (you will feel it overcome the ratchet), then pull it out to about its midpoint. Lotus notes you should hear roughly five clicks and that the ratchet is stiff.
3. Hold the brake pedal down by hand, refit the switch into its bracket, then let the pedal return gently against its stop.
4. Recheck live data. If the readings are out of range, remove the switch and adjust the plunger in or out on the ratchet until they are correct.
5. Clear the codes and road test to confirm they do not return.

Bulletin 2015/03 adds that the plunger should get a pin-head amount of silicone grease spread along the shaft, whether you are refitting the original switch or fitting a new one. Lotus specifies one particular grease and warns that other silicone greases may damage the switch's internal contacts, so use the product named in the bulletin. Cover the pedal pads while you work and clean them afterward so no grease ends up under your foot.

What to Check or Replace at the Same Time

If the ABS light came with a low fluid warning, check the pads and rotors before topping up. The fluid level drops as pads wear because the caliper pistons move out. Track days wear the Evora's large vented rotors quickly. We carry DBA 4000 Series T3 slotted front rotors for the 2009-2017 Evora and a matching DBA T3 slotted rear rotor for the Evora coupe.

For pads, match the compound to how you drive. The DBA Race Performance pad set for the 2010-2015 Evora suits hard road and track use, while EBC SR-11 sintered front pads for the 2015-2021 supercharged Evora are a dedicated race compound. Early and later cars use different front pad part numbers, so check the listing years against your car. You can also browse all brake pads and brake rotors.

Any time the hydraulics are opened, bleed with fresh fluid of the type printed on your reservoir cap and in the owner's handbook, and inspect the brake hoses for rubbing or cracking.

How Hard Is This Job?

Resetting and greasing the brake light switch is a quick job for a confident owner, but the finish depends on a scan tool that can show ABS live data and clear ABS codes. Without one, you can set the plunger to its midpoint and grease it, but you cannot confirm the switch timing against line pressure the way the bulletin intends. Lotus allowed dealers only a small fraction of an hour of labor for the check, which tells you it is not a major job. Wheel speed sensor work is moderate. An ABS module replacement is a dealer or specialist job because it needs the right bleeding procedure and setup with a capable scan tool.

Frequently Asked Questions

Is it safe to drive my Evora with the ABS light on?

The normal brakes still work, but anti-lock and usually stability control are switched off, so the car can lock wheels in a hard stop or on a wet road. Drive gently and get the code read soon. If the red brake warning light is also on, stop and check the fluid before driving further.

Does the ABS light mean my ABS module has failed?

Usually not. Lotus's own bulletins say to check and set the brake light switch first, before replacing the module, because an incorrectly set switch can generate the same pressure sensor fault code.

What does code C0340 mean on a Lotus Evora?

C0340 is a brake light switch fault. Lotus traced many cases to sticking switch plungers and issued bulletin 2015/03, which calls for greasing the plunger with a specific silicone grease.

What does code C0460 mean on a Lotus Evora?

C0460 is logged as a pressure sensor failure. Bulletin 2013/04 explains it can be set when the brake light switch plunger is out of adjustment, so the brake lights come on after line pressure has already risen.

Can worn brake pads turn on the ABS light?

Not directly, but worn pads let the fluid level drop, which can trigger a brake warning. Check pad thickness and fluid level whenever a brake warning appears.

Why did the ABS light come on after I replaced my pads?

If anything in the footwell or at the pedal was disturbed, the brake light switch plunger may have moved. A wheel speed sensor connector knocked loose during the job is the other common cause.

Sources

1. Lotus Service Bulletin 2013/04 (NHTSA) - C0460 and P0571 codes, two-stage brake light switch, live data checks, plunger adjustment, pressure sensor non-serviceable
2. Lotus Service Bulletin 2015/03 (NHTSA) - C0340 code, sticking plungers, silicone grease procedure for Evora with Bosch ABS
3. Center for Auto Safety - 2011 Lotus Evora - list of Evora brake TSBs including the 2013 brake hose and pipe routing inspection
4. Bosch Mobility - Wheel speed sensor - how active Hall-effect wheel speed sensors feed ABS and ESP