C1237 Primary brake pressure sensor signal (Hyundai) or rear wheel speed sensor (Ford)

ABS code C1237

C1237 in short

C1237 means different things by make. On Hyundai Sonatas it is the primary pressure sensor signal in the brake hydraulic unit, and owners report costly unit repairs. On Ford it points to a rear wheel speed sensor. Treat any C1237 with brake warnings as a reason to have the brakes inspected soon.

On Hyundai, owner readouts call C1237 the primary pressure sensor signal in the active hydraulic booster. One owner saw the sensor value jump from 0.3 to 78 bar while supply voltage stayed steady, and a dealer charged for a hydraulic power unit.

On Ford, an Explorer owner was told C1237 was the rear speed sensor, and Ford bulletins list C1237 with C1235 and C1236 on differential-mounted rear sensors. Other Ford bulletins pair it with C1229 and C1230.

The meanings are not the same, so check the make before acting.

Pick your make

C1237 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

  1. Hyundai brake hydraulic unit pressure sensor

    Supported by vehicle data
    Why it ranks here
    Three Sonata complaints quote C1237 as the primary pressure sensor signal and describe hydraulic unit repairs.
    What would change this
    Rises if pressure readings jump with no brake input. Falls if readings are normal.
    How to test the brake system control module (abs module)

  2. Ford rear wheel speed sensor, wiring or tone ring

    Supported by vehicle data
    Why it ranks here
    An Explorer owner was told the rear speed sensor failed, and Ford groups C1237 with the other wheel speed codes.
    What would change this
    Rises if the rear wheel speed reads zero. Falls if all wheel speeds read normally.

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Read all ABS and brake codes and live data. On a Hyundai compare the pressure sensor values with the brake pedal released and pressed; on a Ford compare the four wheel speeds.

    Low riskTool: scan tool with ABS data

Symptoms

  • ABS light on
  • Brake warning message on a Hyundai
  • Pedal feels different or brakes weak 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):Hyundai owners report repair bills near $3,000 for the hydraulic unit; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Hyundai

  • 2009–2014 · Sonata

    Supported by vehicle data

    Sonata owners quote C1237 as the primary pressure sensor signal. Based on owner complaints.

Ford

  • 2000–2005 · F-150

    Supported by vehicle data

    Ford bulletins 15022 (2000-2001) and 18450 (2005) list C1237 with an ABS light and the C1229/C1230 codes. Only the NHTSA summaries were read; whether they are current is not verified.

  • 2000–2001 · Expedition

    Supported by vehicle data

    Ford bulletin 15022 lists C1237 with an ABS lamp. Only the NHTSA summary was read.

  • 2002–2004 · Explorer

    Supported by vehicle data

    Ford bulletins 03263 and 14900 group C1237 with rear wheel speed sensor codes. Only the NHTSA summary was read.

  • 03263Status unverified

    ABS lamp with C1235, C1236, C1237

    2002–2004explorer · NHTSA 10008281

    Covers vehicles with a differential-mounted rear wheel speed sensor. Summary only.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 14900Status unverified

    ABS light on with C1230 and/or C1237

    2002explorer · NHTSA 620216

    Summary only; the repair is not stated.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 15022Status unverified

    ABS lamp on with C1230, C1229 or C1237

    2000–2001explorer, expedition, excursion, f-150, ranger · NHTSA 622841

    Summary only; the repair is not stated.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 18450Status unverified

    False ABS activation or ABS light with C1175, C1236, C1230 or C1237

    2005f-150 · NHTSA 10014638

    Summary only; the repair is not stated.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Mercury

  • 2002–2004 · Mountaineer

    Supported by vehicle data

    Ford bulletins 14900 and 03263 cover the Mountaineer with C1237 and an ABS light. Only the NHTSA summaries were read.

All ABS, traction and stability control codes

C1237 questions

Does C1237 mean the same on Ford and Hyundai?

No. Owners quote it as a pressure sensor signal on Hyundai Sonatas and a rear wheel speed sensor on Ford Explorers.

Sources and review

  1. NHTSA complaint ODI 11435765: 2012 Hyundai Sonata C1237 hydraulic power unit — NHTSA Office of Defects Investigation
  2. NHTSA complaint ODI 10142417: 2002 Ford Explorer ABS light and C1237 — NHTSA Office of Defects Investigation
  3. NHTSA complaint ODI 11557250: 2012 Hyundai Sonata Hybrid C1237 and P1886 — NHTSA Office of Defects Investigation
  4. NHTSA complaint ODI 11301374: 2009 Hyundai Sonata HECU failure with C1237 — NHTSA Office of Defects Investigation
  5. Ford 03263: ABS lamp with C1235, C1236, C1237 on vehicles with differential-mounted rear wheel speed sensor (2002-2004 Explorer, Mountaineer, Aviator) — NHTSA manufacturer communications (flat file, NHTSA ID 10008281)
  6. Ford 15022: ABS lamp on with C1230, C1229 or C1237 (2000-2001 Explorer, Expedition, Excursion, F-150, Ranger, Super Duty, E Series) — NHTSA manufacturer communications (flat file, NHTSA ID 622841)
  7. Ford 18450: false ABS activation or ABS light with C1175 or C1236, or C1230 or C1237 (2005 F-150) — NHTSA manufacturer communications (flat file, NHTSA ID 10014638)
  8. Ford 14900: ABS light on with C1230 and/or C1237 (2002 Explorer, Mountaineer) — NHTSA manufacturer communications (flat file, NHTSA ID 620216)
Last reviewed
Written by
Saurabh K.
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