C1236: Left rear wheel speed sensor input missing (Ford)
Ford ABS code C1236
Severity: Inspect soon
The ABS lamp is on and ABS is off, and on Windstars the code appears with a failing ABS module and a brake warning light.
It gets more serious if:
- Stop: Stop and have the vehicle inspected if a red BRAKE warning light comes on or the brake pedal feels different.
C1236 in short
On Ford, C1236 means the ABS module is not getting a signal from the left rear wheel speed sensor. The cause is often the sensor or its wiring, and on some Windstars the ABS module. ABS stays off, so have it checked soon, and stop if the red brake light comes on.
The ABS module needs each wheel's speed. C1236 is set when the left rear input is missing or faulted.
Ford bulletins pair C1236 with C1175 and C1235 for rear sensors, including ones mounted on the differential on Mountaineer-era vehicles.
On Windstars, C1236 often appears with C1235 and C1185 (power relay fault), and owners link it to failing ABS module solder.
Pick your make
C1236 is a manufacturer-specific code: its meaning depends on who built the car.
Other makes: meaning not verified. Check with a scan tool that reads manufacturer definitions.
Most likely causes
Cause 1: Rear wheel speed sensor or wiring
Supported by vehicle data- Why it ranks here
- Ford bulletins list C1236 under the rear wheel speed sensor.
- What would change this
- Rises if live rear speed drops out.
Cause 2: ABS module or power relay (Windstar)
Supported by vehicle data- Why it ranks here
- Windstar owners see C1235/C1236 with C1185 and a failed module.
- What would change this
- Rises if C1185 also stored.
What to test first
Start at step 1. Each result tells you what it means and where to go next.
Step 1: Read all ABS codes.
IfC1185 stored too
It meansModule or power relay.
IfOnly C1235/C1236
It meansRear sensors.
Symptoms
- ABS lamp on
- ABS not engaging, brake light also on Gets more serious: stop and have it checked.
How to fix
This is a safety-critical system, so we explain the code but don't give repair steps. Have it inspected by a qualified technician.
Parts and cost context
- Brake system control module (ABS module):Labour varies; get a quote.
Labor varies by vehicle and shop; get a quote before you approve a repair.
Compare used part prices on PartPriceGuideOn your vehicle
FordYour car
2005 · Freestar
Supported by vehicle dataFord bulletin 052510 ties C1175/C1236 to the rear wheel speed sensor.
052510Status unverified
ABS light with C1175/C1236 and C1165/C1235
2005freestar · issued · NHTSA 10019009
Rear wheel speed sensor fault pair; summary only.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
MercuryYour car
2004 · Mountaineer
Supported by vehicle dataBulletin 03263 covers C1235/C1236/C1237 with a differential-mounted sensor.
03263Status unverified
ABS lamp with C1235, C1236, C1237
2004mountaineer · issued · NHTSA 10008281
Vehicles with differential-mounted rear sensor; summary only.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
Related codes
Sources and review
- NHTSA complaint ODI 10217805: 2003 Ford Windstar, C1236 LR wheel speed sensor input missing
- NHTSA complaint ODI 10274301: 2002 Ford Windstar ABS codes
- Ford 052510: ABS LIGHT ON AND DTCS C1175/C1236, C1165/C1235 - REAR WHEEL SPEED SENSOR. *TT
- Mercury 03263: ANTI-LOCK BRAKE SYSTEM (ABS) LAMP ILLUMINATED AND DIAGNOSTIC TROUBLE CODE (DTC) C1235, C12
- Lincoln 07172: SOME 2007 EDGE/MKX VEHICLES BUILT BEFORE 6/1/07 (FWD ONLY) MAY EXHIBIT AN ABS LAMP ON C11
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error