C0161 ABS computer does not trust the brake pedal switch signal

ABS brake switch circuit

C0161 in short

C0161 means the ABS and stability computer does not trust the brake pedal switch signal, so it cannot tell when you are braking. On GM cars and trucks this often shows up as brake lights that stay on or fail, no cruise control and a stability warning. Get it checked soon because brake lights may be affected.

The ABS and stability computer compares the brake pedal position signal with brake pressure and vehicle speed. GM-based Saab service information says the code sets when the pedal signal does not match what the computer expects, for example the pedal signal never changes over several launches from a stop.

Because the same pedal signal also runs the brake lights and cruise control, GM bulletins list C0161 together with brake lights that stay on, brake lights that work intermittently, cruise control that quits and a stability control message. Some bulletins pair it with C0277.

On 2012 and newer GM trucks the old brake switch was replaced by a dual brake pedal position sensor, so the same code points at a different part on those vehicles.

Most likely causes

  1. Brake pedal position sensor needs calibration or replacement

    Supported by vehicle data
    Why it ranks here
    GM bulletin SB-08-05-22-005 for the 2008-2009 G8 says to calibrate the brake pedal position sensor, and Saab service information gives calibration as the first repair once installation is checked. The bulletin status is unverified.
    What would change this
    Rises if the brake lights stay on or flicker and a scan tool shows the pedal signal not changing with the pedal. Falls if the lights and the pedal signal behave normally and the code stays away after calibration.

  2. Pedal sensor or switch out of position after repairs or wear

    Possible — needs testing
    Why it ranks here
    Saab service information tells the technician to check that the pedal position sensor and the pedal are installed correctly before anything else, so a misaligned sensor is a listed cause.
    What would change this
    Rises if the code appeared after brake or pedal work. Falls if the sensor mounting is secure and aligned.

  3. Brake held on while accelerating (two-footed driving)

    Possible — needs testing
    Why it ranks here
    Saab service information says the code can set when the brake is applied while accelerating, so a habit rather than a fault can set it.
    What would change this
    Rises if the code is a one-time event with no brake light fault. Falls if the brake lights or cruise control also misbehave.

  4. Brake control module fault

    Possible — needs testing
    Why it ranks here
    Saab service information lists module replacement only after the pedal sensor checks and calibration fail, so it ranks last.
    What would change this
    Rises only after the sensor, wiring and calibration are cleared and the code returns. Falls if calibration clears it.
    How to test the brake system control module (abs module)

What to test first

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

  1. Watch the brake lights while a helper presses and releases the pedal, and note whether cruise control works.

    Low risk

  2. Have a shop check that the brake pedal sensor is installed correctly and run the pedal position sensor calibration with a scan tool, then clear the code and road test.

    Best left to a shopTool: scan tool

    Warning:Brake, stability and wiring checks need scan tools and a lifted vehicle. Let a shop do this.

  3. A shop should test the sensor wiring and, if it is sound, the brake control module.

    Best left to a shop

    Warning:Brake, stability and wiring checks need scan tools and a lifted vehicle. Let a shop do this.

Symptoms

  • ABS or service stability warning light on
  • Brake lights that stay on or work intermittently Gets more serious: stop and have it checked.
  • Cruise control not working
  • Extended pedal travel to shift out of park on some GM cars

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):Replace the module only after the pedal sensor, wiring and calibration are cleared. Labor varies; 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

Pontiac

  • 2008–2009 · G8

    Supported by vehicle data

    GM bulletin for C0161 on the 2008-2009 G8: brake lights stay on and cruise is off; calibrate the brake pedal position sensor.

  • 2005–2009 · G6

    Supported by vehicle data

    GM bulletin: C0161 and C0277 with faulty brake lights and cruise control on these 2004-2009 mid-size cars.

  • SB-08-05-22-005Status unverified

    Brake lights on, cruise off, stability message, C0161 (G8)

    2008–2009g8 · NHTSA 10026626

    Calibrate the brake pedal position sensor with the scan tool; the condition can be intermittent.

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

  • SB-08-05-22-009A (pontiac)Status unverified

    Intermittent brake lights, stiff shift out of park, cruise off, C0161/C0277

    2005–2009g6 · NHTSA 10032206

    Lists C0161 and C0277 with intermittent brake light faults, extended travel to shift out of park and no cruise control; the repair is outlined in the full bulletin.

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

Chevrolet

  • 2004–2007 · Malibu

    Supported by vehicle data

    GM bulletin: C0161 and C0277 with faulty brake lights and cruise control on these 2004-2009 mid-size cars.

  • 2008 · Malibu Classic

    Supported by vehicle data

    GM bulletin: C0161 and C0277 with faulty brake lights and cruise control on these 2004-2009 mid-size cars.

  • 2012 · Express

    Supported by vehicle data

    GM information bulletin for 2012-2013 full-size trucks and SUVs: dual brake pedal position sensor and C0161/C0277.

  • 2012 · Silverado 1500

    Supported by vehicle data

    GM information bulletin for 2012-2013 full-size trucks and SUVs: dual brake pedal position sensor and C0161/C0277.

  • 2012 · Suburban

    Supported by vehicle data

    GM information bulletin for 2012-2013 full-size trucks and SUVs: dual brake pedal position sensor and C0161/C0277.

  • SB-08-05-22-009AStatus unverified

    Intermittent brake lights, stiff shift out of park, cruise off, C0161/C0277

    2004–2008malibu, malibu-classic · NHTSA 10032206

    Lists C0161 and C0277 with intermittent brake light faults, extended travel to shift out of park and no cruise control; the repair is outlined in the full bulletin.

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

  • PIT-5122-C (chevrolet)Status unverified

    Service stability, low power, brake lights, C0161/C0277 on 2012+ trucks

    2012avalanche, express, silverado-1500, suburban, tahoe · NHTSA 10044879

    Explains that 2012 models use a dual brake pedal position sensor in place of the old brake switch, and covers C0161 and C0277 with stability, brake light and cruise faults.

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

Saturn

  • 2007–2009 · Aura

    Supported by vehicle data

    GM bulletin: C0161 and C0277 with faulty brake lights and cruise control on these 2004-2009 mid-size cars.

  • SB-08-05-22-009A (saturn)Status unverified

    Intermittent brake lights, stiff shift out of park, cruise off, C0161/C0277

    2007–2009aura · NHTSA 10032206

    Lists C0161 and C0277 with intermittent brake light faults, extended travel to shift out of park and no cruise control; the repair is outlined in the full bulletin.

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

Cadillac

  • 2012 · Escalade

    Supported by vehicle data

    GM information bulletin for 2012-2013 full-size trucks and SUVs: dual brake pedal position sensor and C0161/C0277.

  • 2012 · Escalade ESV

    Supported by vehicle data

    GM information bulletin for 2012-2013 full-size trucks and SUVs: dual brake pedal position sensor and C0161/C0277.

  • PIT-5122-CStatus unverified

    Service stability, low power, brake lights, C0161/C0277 on 2012+ trucks

    2012escalade, escalade-esv · NHTSA 10044879

    Explains that 2012 models use a dual brake pedal position sensor in place of the old brake switch, and covers C0161 and C0277 with stability, brake light and cruise faults.

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

GMC

  • 2012 · Yukon

    Supported by vehicle data

    GM information bulletin for 2012-2013 full-size trucks and SUVs: dual brake pedal position sensor and C0161/C0277.

  • 2012 · Savana

    Supported by vehicle data

    GM information bulletin for 2012-2013 full-size trucks and SUVs: dual brake pedal position sensor and C0161/C0277.

  • 2012 · Sierra 1500

    Supported by vehicle data

    GM information bulletin for 2012-2013 full-size trucks and SUVs: dual brake pedal position sensor and C0161/C0277.

  • 2012 · Yukon XL

    Supported by vehicle data

    GM information bulletin for 2012-2013 full-size trucks and SUVs: dual brake pedal position sensor and C0161/C0277.

  • PIT-5122-C (gmc)Status unverified

    Service stability, low power, brake lights, C0161/C0277 on 2012+ trucks

    2012savana, sierra-1500, yukon, yukon-xl · NHTSA 10044879

    Explains that 2012 models use a dual brake pedal position sensor in place of the old brake switch, and covers C0161 and C0277 with stability, brake light and cruise faults.

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

  • C0186Sideways (lateral) acceleration sensor signal faulty or not believable

    Same system Possible — needs testing

    GM stability faults often appear together with this code when the stability computer has lost its inputs.

All ABS, traction and stability control codes

C0161 questions

Why do my brake lights and cruise control fail with C0161?

GM bulletins list C0161 with brake lights that stay on or work intermittently and cruise control that stops, because the same brake pedal signal feeds all three.

Sources and review

  1. GM SB-08-05-22-009A: intermittent brake lights, extended travel to shift out of park, cruise inoperative, DTCs C0161/C0277 — General Motors via NHTSA
  2. GM PIT-5122C: service stability message, low power, brake lights and cruise, DTC C0161 and/or C0277 (2012-2013 trucks and SUVs) — General Motors via NHTSA
  3. GM SB-08-05-22-005: brake lights stay on, cruise inoperative, stability off message, DTC C0161 (2008-2009 Pontiac G8) — General Motors via NHTSA
  4. DTC C0161 (Saab 9-4X 2011 service information) — Saab / General Motors (saabwisonline.com mirror)
  5. GM 3741A: service stability light on, C0186 C0196 C0283 C0287 C0290 C0292 C0455 C0550 (2006 TrailBlazer family) — General Motors via NHTSA
Last reviewed
Written by
Saurabh K.
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