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P0606CriticalEngine

P0606: How to Diagnose & Fix — PCM Processor Fault

5 vehicles · 4 makes · $300-$1,200 repair

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How to diagnose and fix P0606: most-reported vehicles

Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.

Citroen C3 · 2002–2016

Community reported
95 owners
Link to this issueError Codes:C1404C1414P0606

The C3 Mark I and II experience electric power steering failures caused by the column-mounted EPS motor and its control ECU. The steering becomes heavy without warning, which is particularly dangerous at low speeds during parking.

Common Symptoms

  • Sudden heavy steering
  • Power steering warning light
  • Intermittent assist loss
  • Steering column noise

How to Fix

Replace the EPS motor and control unit assembly. Some specialist repairers can refurbish the ECU by resoldering cracked joints. Check for a Citroën recall on your VIN.

Typical repair cost:$300 - $900

Research This Issue

Based on 95 owner reports

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Community Reported
High Confidence95 owner reportsReviewed Invalid Date

Jeep Avenger · 2023–2024

Community reported
85 owners
Link to this issueError Codes:P0606P1A0F

The Jeep Avenger's 1.2L mild hybrid powertrain experiences frequent Start & Stop system malfunctions. The system may fail to restart the engine properly, cause delayed or sluggish restarts, or stall the engine entirely during stop-and-go driving. The issue is linked to the mild hybrid system's integration with the 48V electrical architecture and MCU software calibration.

Common Symptoms

  • Engine fails to restart after automatic stop at traffic lights
  • Delayed or slow engine restart when releasing brake pedal
  • Random engine stalling while driving at low speeds
  • Start & Stop warning light illuminated on dashboard
  • Jerky transitions between electric assist and engine power

How to Fix

Visit a Jeep dealer for an MCU (Motor Control Unit) software update that recalibrates the Start & Stop system behavior. The dealer will check error logs and reflash the MCU with updated firmware. If the issue persists after the software update, the 48V battery or belt-starter-generator (BSG) may need inspection or replacement.

Owner tips & cautions

  • TipRequest an MCU software update at your first dealer visit — many stalling and Start & Stop issues are resolved by a firmware reflash alone.
  • TipIf the Start & Stop system is acting erratically, you can manually disable it each drive by pressing the Start & Stop button on the console until a permanent software fix is applied.
Typical repair cost:$0 - $300
Sources for this issue (1)
  • Jeep Avenger Breakdown Issues — Jeep Avenger Forumowner-report

Research This Issue

Based on 85 owner reports

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Community Reported
Medium Confidence85 owner reportsLast reported by owners Mar 2026Reviewed Mar 2026

Hyundai Venue · 2020–2022

Link to this issueError Codes:P0606

Venue owners, concentrated on the 2020 model, report the engine unexpectedly shutting off, particularly while slowing or coming to a complete stop, sometimes with rough idle. Some cases are traced to a faulty or corroded wiring-harness connector near the battery causing intermittent power interruptions. CarComplaints and YourMechanic both document the slow-down/stop shut-off pattern, with stalling reported at low mileage.

Common Symptoms

  • Engine shuts off when slowing or stopping
  • Random stalling while driving / loss of power
  • Rough idle
  • No-start or hard-start after the engine dies

How to Fix

Have the dealer inspect and repair the battery/wiring-harness connector and check for stored DTCs and applicable TSBs; corroded or loose connectors should be cleaned or replaced. Persistent stalling the dealer cannot resolve over multiple visits may qualify under state lemon laws. On 2024 models, rule out the separate EGR-valve recall (24V308).

Sources for this issue (2)
  • 2020 Hyundai Venue Engine Problems - CarComplaints.comarticle
  • Hyundai Venue: When I slow down and stop the car, engine shuts off - YourMechanicarticle

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Community Reported
Low ConfidenceVerifiedReviewed Jun 2026

Toyota Camry · 2007–2010

Link to this issueError Codes:P0138P0158P0606P2195P2197

Toyota T-SB-0001-10 Rev1 covers specified 2007-2009 Camry VDS BK46K and 2010 VDS BK3EK applications. P0138/P0158 may result from incorrect air-fuel-sensor response, and P0606 may also be present due to incorrect downstream O2-sensor operation. Toyota distinguishes these paths using the complete DTC set, freeze-frame air-fuel/O2 voltage and downstream O2 impedance, followed by circuit inspection. It does not describe every P0606 as a sensor fault or support the original 2AZ-FE, 2006-2012, VSC/TRAC or battery claims.

Common Symptoms

  • Malfunction indicator lamp with a covered combination of P0138, P0158 and/or P0606

How to Fix

Confirm the covered VDS/2GR-FE application and capture all DTCs plus freeze-frame data. Follow T-SB-0001-10 Rev1: use the specified air-fuel/O2 freeze-frame gates for P0138/P0158, and for a qualifying P0606 path verify O2 Sensor 2 voltage above 1.10 V and/or impedance above 300 ohms at normal operating temperature, then inspect the circuit for open, short or high resistance. Replace only the bulletin-identified sensor when every gate is met; otherwise continue repair-manual P0606 diagnosis. Do not buy the prior sensor from this card.

Owner tips & cautions

  • TipSave the complete DTC set and freeze-frame air-fuel/O2 values before clearing codes; the bulletin's path depends on the combination and measured data.
  • WarningDo not treat a standalone P0606 or a non-covered VDS/engine as an oxygen-sensor diagnosis. Follow the applicable repair manual instead.
Sources for this issue (1)
  • Toyota T-SB-0001-10 Rev1: P0138, P0158 and/or P0606 Diagnostic Tipstsb

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Manually Verified
High ConfidenceVerifiedReviewed Jul 2026

Toyota Matrix · 2005–2008

Link to this issueError Codes:U0100P0606

Toyota recalled roughly 1.13 million 2005-2008 Corolla and Corolla Matrix vehicles built with the 1ZZ-FE engine and two-wheel drive because the engine control module was improperly manufactured. Cracks can develop at solder points or on varistors on the ECM circuit board. Symptoms escalate from an illuminated check engine light to abnormally harsh automatic transmission shifting, a no-start condition, and in the worst case the engine shutting off while the vehicle is being driven. Toyota's internal campaign designation is A0J. Owners of 2004 cars report the same failure pattern with a mechanically similar module even though that year sits outside the recall population, so a 2004 with these symptoms should still have the ECM considered. Note the recall is limited to 2WD 1ZZ-FE cars - AWD and XRS models were built with different modules.

Common Symptoms

  • Engine stalls without warning while driving
  • Engine cranks but will not start
  • Harsh or abrupt automatic transmission shifts
  • Check engine light on with no obvious mechanical cause
  • Intermittent loss of communication with the scan tool

How to Fix

Free remedy under NHTSA recall 10V384000 / Toyota A0J: dealers inspect and reprogram or replace the ECM at no charge. Check the VIN on the NHTSA or Toyota recall lookup first, because many of these cars were remedied years ago. Outside the recall population the fix is ECM replacement or board-level repair (a reflow/reman of the original module is generally far cheaper than a new unit and keeps the immobilizer pairing intact). Do not chase a random no-start with parts before ruling the ECM in or out.

Typical repair cost:$0 - $1,200
Sources for this issue (3)
  • Toyota Safety Recall A0J - Certain 2005-2008 Corolla and Matrix ECM (NHTSA 10V384)recall
  • Toyota Matrix 2005 Engine and Engine Cooling Recall, NHTSA Campaign 10V384000recall
  • Toyota Matrix 07 ECM problem - ToyotaNationforum

Research This Issue

GoogleRedditYouTubeNHTSA
Community Reported
High ConfidenceVerifiedReviewed Aug 2026

Find P0606 by make

Browse every documented model and issue for your make.

Citroen · 1 issueHyundai · 1 issueJeep · 1 issueToyota · 2 issues

P0606 code reference

General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.

Frequently asked questions

What does P0606 mean?

P0606 stands for "PCM Processor Fault." P0606 indicates an internal processor or performance fault within the powertrain control module (PCM) — essentially the engine's main computer has detected that one of its own internal circuits or processors is not functioning correctly. Because the PCM controls fuel, ignition, and many other functions, an internal fault can affect almost any aspect of engine operation. Symptoms range from no obvious effect to stalling, no-start, erratic running, or multiple unrelated trouble codes appearing together. This often points to the module itself, though power and ground supply issues can mimic it.

What are the most common causes of P0606?

The most common causes of P0606 are: Poor power or ground supply to the PCM, Corroded, loose, or damaged PCM connectors, Low system/battery voltage or charging system fault, Water intrusion or corrosion at the module, Internal PCM hardware/processor failure, Failed or corrupted PCM software needing reflash, Wiring damage affecting the PCM power/ground circuits. The specific cause varies by vehicle.

How much does it cost to fix P0606?

Repair costs for P0606 range from $300 to $1,200, depending on the vehicle and root cause.

Which vehicles are affected by P0606?

Au7o has documented P0606 across 5 vehicle models from 4 manufacturers: Citroen, Hyundai, Jeep, Toyota.

Related codes

  • P0601 · Internal Control Module Memory Check Sum Error
  • P0603 · Internal Control Module Keep Alive Memory (KAM) Error
  • P0605 · Internal Control Module Read Only Memory (ROM) Error
  • P0607 · Control Module Performance
  • 00522 · Engine Coolant Temperature Sensor (G62): Open Circuit / Short to Positive (B+)
  • 16500 · Engine Coolant Temp. Sensor (G62): Implausible Signal
  • 16502 · Engine Coolant Temperature Sensor (G62): Signal too High
  • 16566 · Mass Air Flow Sensor Signal Too Low (VAG)
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.

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