P0606 A control module found a fault in its own processor or programming

Control module processor performance (ECM/PCM processor fault)

P0606 in short

P0606 means a control module, usually the engine computer, found a fault in its own processor or programming. Low battery voltage, poor module power or ground, and software that needs updating are common causes before the module itself. Get it checked soon, and stop driving if the brakes feel hard or the engine stalls.

Engine computers and many other modules constantly check their own processor and memory. If a check fails, or the module finds it is not programmed correctly, it stores P0606. In GM service information the check runs whenever system voltage is above about 6 volts.

The code does not always come from the engine computer. GM notes that P0606 and related processor codes can be stored by several modules, and on 2019 and later Silverado and Sierra trucks the brake module has set it from low voltage, along with a hard pedal and reduced power messages. On Ford Fiesta and Focus with the DPS6 transmission it shows up with network codes.

Because self-checks depend on clean power, diagnosis starts with the battery, cables, grounds and power feeds, then reprogramming. Replacing the module comes last: GM told dealers to stop replacing engine computers on some 2017 vehicles where a camshaft sensor fault was the real trigger.

Most likely causes

  1. Low battery voltage or a poor module power or ground connection

    Common general cause
    Why it ranks here
    GM service information has technicians confirm the battery is charged, the cables are clean and tight, and the module grounds and power feeds are good before anything else, and GM bulletins show low voltage making a brake module set P0606 on 2019–2026 trucks.
    What would change this
    Rises if the battery tests weak, P0562 is stored too, or the code appeared after a flat battery or jump start. Falls if battery, charging voltage and grounds all test good.

  2. Code stored by another module (brake, transmission or body module)

    Supported by vehicle data
    Why it ranks here
    GM says P0606 can be shared by several modules, and its truck bulletins trace it to the brake module. Ford’s DPS6 bulletin lists P0606 with U0100 and U0101 network codes on the Fiesta and Focus.
    What would change this
    Rises if a full-vehicle scan shows P0606 in a module other than the engine computer, or with brake C-codes or U-codes. Falls if only the engine computer stores it.

  3. Module not programmed correctly or needing a software update

    Supported by vehicle data
    Why it ranks here
    GM service information lists a module that is not programmed or programmed incorrectly as a cause, and Toyota has a bulletin for P0606 with P0604 and P0607 on 2003–2004 Camry and Solara.
    What would change this
    Rises if a dealer finds newer software for your VIN. Falls if the module is already up to date.

  4. Ignition switched on too soon after reconnecting the battery (Subaru Forester Turbo, WRX)

    Supported by vehicle data
    Why it ranks here
    Subaru says turning the ignition back on within a minute of first switching it off after a battery reconnection can set P0606 on these models. It is narrow, so it ranks below general causes.
    What would change this
    Rises if the code appeared right after battery work on one of these models and does not return once cleared. Falls if it returns on its own.

  5. Camshaft sensor fault confusing the engine computer (some 2017 GM vehicles)

    Supported by vehicle data
    Why it ranks here
    GM bulletin 17-NA-132 tells dealers to test and repair the camshaft sensor and stop replacing the engine computer when P0606 sets on some 2017 Silverado, Sierra, Express, Savana and Cruze.
    What would change this
    Rises on those vehicles if the cam sensor or its signal tests faulty. Falls on other vehicles.
    How to test the camshaft position sensor

  6. Internal failure of the module itself

    Possible — needs testing
    Why it ranks here
    GM service information replaces the module only after power, ground and programming checks pass, so it is the last cause to accept.
    What would change this
    Rises if the code returns right after a clean reprogram with good power and grounds. Falls if any of those checks fail.
    How to test the engine control module (ecm / pcm)

What to test first

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

  1. Scan every module, not just the engine computer, and note which module stored P0606 and what other codes are with it.

    Low riskTool: scan tool that reads all modules

  2. Test the battery and charging voltage, and check that the battery cables and main grounds are clean and tight.

    Low riskTool: battery tester or multimeter

  3. Ask a dealer whether your VIN has a software update or bulletin for P0606.

    Low risk

  4. Have a shop voltage-drop test the module power feeds and grounds, then reprogram the module.

    Best left to a shopTool: digital multimeter, programming tool

    Warning:Probing module connectors can damage terminals and a failed reprogram can disable the car. Leave this to a shop.

Symptoms

  • Check engine light with no other change
  • Reduced engine power or Speed Limited message
  • Intermittent no start or loss of transmission engagement (Ford Fiesta and Focus with DPS6)
  • Hard brake pedal, or a Service Brake System message Gets more serious: stop and have it checked.
  • Engine stalls while driving Gets more serious: stop and have it checked.

How to fix

  1. Have the battery and charging system tested; many parts stores do this free.

  2. Ask a dealer whether your VIN has a software update or bulletin for P0606 before agreeing to a new computer.

Parts and cost context

  • Engine control module (ECM / PCM):Replace only after power, ground and programming checks pass. A replacement module has to be programmed to the vehicle. Labour 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

Ford

  • 2011–2016 · Fiesta

    Supported by vehicle data

    With the DPS6 automatic, Ford bulletin 16-0044 lists P0606 with U0100, U0101, U1013 and U3003 and symptoms of no start or loss of drive. The transmission side is the focus, not the engine computer alone. Whether the bulletin is still current is not verified.

  • 2012–2016 · Focus

    Supported by vehicle data

    Same DPS6 bulletin as the Fiesta: P0606 with network codes, no start or loss of drive. Whether the bulletin is still current is not verified.

  • 16-0044Status unverified

    DPS6: no start, loss of engagement or power with U0100, U0101 and/or P0606

    2011–2016fiesta, focus · issued · NHTSA 10075274

    Intermittent loss of transmission engagement, no start or loss of power with the check engine light on.

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

Chevrolet

  • 2019–2020 · Silverado 1500

    Supported by vehicle data

    GM says the brake module can set P0606 from low voltage, with a hard pedal and Service Brake System message; following the engine-computer P0606 test can lead to the wrong repair. Check the battery and charging system first. Whether the bulletin is still current is not verified.

  • 3164AStatus unverified

    SES light with P0606, reduced power, possible stall

    2004trailblazer · NHTSA 10017230

    P0606 with reduced engine power and a possible stall. Also covers GMC Envoy, Buick Rainier and Oldsmobile Bravada.

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

  • PIT5634Status unverified

    Brake module sets P0606 from low voltage, hard brake pedal

    2019silverado-1500 · issued · NHTSA 10151841

    Low voltage can make the EBCM set P0606 with reduced power, Service Brake System and a hard pedal; P0606 diagnostics can lead to a wrong repair. Also covers GMC Sierra 1500.

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

  • 20NA073Status unverified

    Loss of brake assist, P0606 with brake codes or P25A2

    2019–2020silverado-1500 · issued · NHTSA 10181688

    Brake pedal travel and feel may change, with P0606 and brake C-codes or P25A2. Also covers Sierra 1500 and other GM models.

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

  • 17-NA-132Status unverified

    Test the cam sensor before replacing the ECM for P0606

    2017silverado · issued · NHTSA 10114033

    Test and repair the camshaft sensor and stop replacing the ECM when P0606 sets. Also covers Sierra, Express, Savana and Cruze.

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

GMC

  • 2019–2026 · Sierra 1500

    Supported by vehicle data

    Same brake-module P0606 pattern as the Silverado; on 2021–2026 trucks GM adds checks for wiring, terminals and communication before parts are replaced. Whether the bulletin is still current is not verified.

  • PIT5634Status unverified

    Brake module sets P0606 from low voltage, hard brake pedal

    2019silverado-1500 · issued · NHTSA 10151841

    Low voltage can make the EBCM set P0606 with reduced power, Service Brake System and a hard pedal; P0606 diagnostics can lead to a wrong repair. Also covers GMC Sierra 1500.

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

  • PIT6522Status unverified

    K160 brake module sets P0606 with P0562 and/or P25A2

    2021–2026sierra-1500, yukon · issued · NHTSA 11033987

    Check for low voltage, wiring, terminal and communication problems before replacing parts.

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

  • P0562System voltage low

    Shares causes Supported by vehicle data

    On GM trucks and SUVs, the brake module can set P0606 together with P0562 when system voltage drops. Check the battery and charging system first.

  • P0607A control module failed one of its internal performance checks

    Same system Supported by vehicle data

    Both are module self-check codes covered by the same GM service procedure, and Toyota’s 2003–2004 Camry bulletin covers them together.

  • U0100Lost communication with the engine or powertrain computer

    Shares causes Supported by vehicle data

    On 2011–2016 Fiesta and 2012–2016 Focus with the DPS6 transmission, Ford lists P0606 with U0100 and U0101 network codes.

  • P25A2Brake control module has asked for the check engine light

    Shares causes Supported by vehicle data

    GM’s brake module can set P0606 with P25A2 and P0562; GM asks dealers to check voltage, wiring and terminals before replacing parts.

  • U0101Lost communication with the transmission computer

    Shares causes Supported by vehicle data

    Ford's DPS6 bulletin lists P0606 with U0100 and U0101 on the 2011–2016 Fiesta and 2012–2016 Focus, with no start or loss of drive.

All Engine computer (ECM/PCM) codes

P0606 questions

Do I need a new engine computer for P0606?

Not usually as a first step. Check the battery, grounds and software, and confirm which module set the code. GM has warned dealers against replacing engine computers when the real fault was elsewhere.

Why does my truck show P0606 with a hard brake pedal?

On 2019 and later Silverado and Sierra, the brake module can set P0606 when voltage drops. Stop driving and have the brakes and battery checked.

Sources and review

  1. GM bulletin 3164A: SES light with P0606, reduced engine power and possible stall (2004 TrailBlazer, Envoy, Rainier, Bravada) — General Motors / NHTSA
  2. GM PIT5634: P0606 set by the EBCM from low voltage, hard brake pedal (2019 Silverado 1500, Sierra 1500) — General Motors / NHTSA ,
  3. GM bulletin 20NA073: loss of brake assist, P0606 with C-codes or P25A2 (2019–2020 Silverado, Sierra and others) — General Motors / NHTSA ,
  4. DTC P0601–P0604, P0606, P0607, P0610, P062B, P062F, P0630, P16F3 or P2610 (ECM, LFW/LFX), 2011 Saab 9-4X service information — Saab Automobile / General Motors (Saab WIS online archive)
  5. GM PIT6522: K160 brake module sets P0606 with P0562 and/or P25A2 (2021–2026 trucks and SUVs) — General Motors / NHTSA ,
  6. GM bulletin 05-06-04-060A: control module DTCs P0601–P0606, P062F, P06F3, P1621 shared across modules — General Motors / NHTSA ,
  7. Ford TSB 16-0044: DPS6 no start, loss of engagement or power with U0100, U0101, U1013, U3003 and/or P0606 (2011–2016 Fiesta, 2012–2016 Focus) — Ford Motor Company / NHTSA ,
  8. Toyota bulletin 05104: MIL on with P0604, P0606 and/or P0607 (2003–2004 Camry, Solara) — Toyota Motor Sales, U.S.A. / NHTSA ,
  9. Subaru bulletin 07-75-13R: P0606 after battery reconnection (Forester Turbo, WRX) — Subaru of America / NHTSA ,
  10. GM bulletin 17-NA-132: test the camshaft sensor before replacing the ECM for P0606 (2017 Silverado, Sierra and others) — General Motors / NHTSA ,
Last reviewed
Written by
Saurabh K.
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