The code P0606: PCM Processor Fault points out a fault in the Powertrain Control Module (PCM), the vehicle’s main computer, and is most likely caused by an internal failure of the PCM or issues with its connections and power supply.
P0606 quick overview
| Meaning | P0606: PCM Processor Fault |
| Is it serious? | Yes, this code is serious as it indicates a fundamental problem with the vehicle’s main computer (PCM), which can affect the vehicle’s operation and drivability. |
| Possible causes | – Internal fault in the Powertrain Control Module (PCM) – Faulty or damaged wiring to the PCM – Poor or corroded ground connections to the PCM – Electrical issues caused by a faulty charging system |
| How to diagnose? | Check PCM Connections: Inspect the Powertrain Control Module (PCM) for secure connections and any visible damage. Inspect Wiring: Examine the wiring to and from the PCM for any signs of damage, wear, or corrosion. Test Power and Grounds: Perform a test on the power and ground supplies to the PCM. Evaluate Charging System: Check the vehicle’s charging system, including the battery and alternator. Consider PCM Replacement: If other checks are inconclusive, consider replacing the PCM. |
P0606 Meaning
When your car shows the P0606 code, it means there’s a big problem with the computer that controls most of the engine’s functions. Think of it like your car’s brain having trouble. This can cause all sorts of issues, from the engine not running properly to the car not starting at all. The fix usually involves checking all the wires going to the computer, making sure it’s getting power properly, and sometimes replacing the computer itself. It’s a critical issue, so it’s best to get it checked by a professional as soon as possible.
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How to fix P0606 – learn from mechanics
I looked into P0606 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.
Case #1: Mercury
Vehicle Information: 2004 Mercury Sable GS 3.0L
Issue + Repair History:
- MIL lamp on.
- Car had new plugs, fuel filter, etc., a few months ago.
Computer Codes & Descriptions:
- PO316: Random cylinder misfire.
- PO606: PCM malfunction.
Suggestions to Fix Issue:
- Clear codes and retest; if code returns, PCM likely faulty.
- P0606 indicates an internal PCM problem or failure in electronic throttle control.
- Suggestion to replace PCM if issue persists.
- Use Motorcraft parts from Ford, especially for plugs and wires.
Final Fix:
- Sent PCM for repair and update; received another PCM indicating the original was bad.
- Vehicle had to be towed to a Ford dealer for programming due to the P.A.T.S system.
- Continued charging problems and lights flickering after PCM programming.
- Replaced alternator which fixed the problem.
Case #2: Chevrolet
Vehicle Information: 2008 Chevrolet Colorado LS 3.7L
Issue + Repair History:
- Vehicle towed in for not running; displayed multiple codes and difficulty starting.
- Codes included P0300, P0106, P0121, P0606, U0073-00.
- Odometer reading changed overnight.
- Vehicle experienced intermittent miss at idle, surges, and stalling.
Computer Codes & Descriptions:
Other Test Results:
- Fuel pressure: 55-60 at idle and running.
- Battery & charging: 12.59V & 14.2V.
- Grounds: all clean and tight.
- Fuel trim: always stays negative.
Suggestions to Fix Issue:
- Inspect for rodent damage and check PCM pins and connectors.
- Check the 5V reference to sensors; look for rubbed-through wires.
- Replace and program the ECM, focusing on P0606 as an indicator of internal ECM failure.
- Check power and ground at the PCM.
- Consider alternator ripple and its effect on the processor.
Final Fix:
- Replaced PCM, which was flashed, resolving the vehicle’s issues.
Case #3: GMC
Vehicle Information: 2008 GMC Yukon XL 1500 Denali 6.2L
Issue + Repair History:
- Vehicle experienced random no-start or stall issues.
- Initially, no codes were stored; later, it stalled and would not restart.
- Codes P0513 and P0606 appeared.
Computer Codes & Descriptions:
- P0513: Immobilizer key error.
- P0606: PCM processor fault.
Suggestions to Fix Issue:
- Load test all powers and grounds to the PCM.
- Try using a different key to rule out immobilizer issues.
- Diagnose and repair code P0513 for potential hints towards the problem.
- Replace and program the ECM as P0606 indicates a severe internal ECM/PCM issue.
- Communicate with all other modules on the data line to check if it’s a PCM issue.
- Ensure that no other codes like P0602 are stored alongside P0606.
Final Fix:
- Replaced the ECM, followed by programming, which resolved the vehicle’s issues.
Case #4: Volkswagen
Vehicle Information: 2001 Volkswagen Beetle GLS 2.0L
Issue + Repair History:
- Engine light on; no drivability problem.
- Codes: P1152 (long-term fuel trim, system too lean) and P0606 (internal control module processor fault), both intermittent.
Computer Codes & Descriptions:
- P1152: Long term fuel trim additive air, bank 1, range 2, too lean, intermittent.
- PO606: Internal control module; processor fault, intermittent.
Suggestions to Fix Issue:
- Replace Mass Air Flow (MAF) sensor and reset module.
- Check for vacuum leaks, especially the fuel pressure regulator vacuum hose.
- Clear codes and retest.
- Check 5V reference to sensors for any drops.
- Load test power and grounds to the PCM.
- Clean the throttle body.
- Check measuring block 32 for MAF sensor readings.
- Replace both MAF sensor and ECM if necessary.
Final Fix:
- Disconnected and reconnected battery cables.
- Replaced Mass Air Flow Sensor with an OEM part.
- Replaced vacuum line to the pressure regulator with an OEM line.
- Reset basic settings and drove the car to set fuel trim.
- Checked engine and intake for vacuum leaks; none found.
- Vehicle fixed with a new MAF sensor and other adjustments.
- Addresing other codes first helped solve the P0606
Case #5: Ford
Vehicle Information: 2004 Ford Freestar Limited 4.2L
Issue + Repair History:
- Vehicle had P0606 code (PCM Internal communication error) and SES light on.
- PCM was replaced and flashed with the latest calibration, but the issue recurred.
Suggestions to Fix Issue:
- Check OBD2 plug and computer plug for good connections.
- Confirm power and ground connections are secure.
- Check for water leakage on PCM, a common issue.
- Consider the possibility of a faulty charging system affecting the PCM.
- Inspect for aftermarket chips or programming that could impact PCM function.
- Test the charging system, including a ripple test for diodes.
Final Fix:
- Found that the main grounds for the PCM were not good.
- Cleaned the PCM grounds, which resolved the issue. Vehicle ran fine after an eight-hour soak and has been running well for five days.
How to diagnose P0606
I made you an overview of solving this DTC, based on all the advice that was suggested by certified mechanics to address this issue in previously mentioned service cases.
| Advice | Description of Diagnostic Step |
|---|---|
| Replace and Reprogram PCM | If P0606 recurs, consider replacing the Powertrain Control Module (PCM) and reprogramming it. |
| Check Power and Ground Connections | Ensure all power and ground connections to the PCM are secure and intact. |
| Inspect PCM Connectors and Wiring | Look for any issues with PCM connectors and wiring, including corrosion or damage. |
| Evaluate Charging System | Check the vehicle’s battery and alternator for any issues that could affect the PCM. |
| Test for Aftermarket Modifications | Confirm if any aftermarket chips or programming could be impacting PCM performance. |
| Consider Internal Failure of PCM | P0606 often indicates an internal issue with the PCM, necessitating its replacement. |
| Clean and Secure Grounds | Clean and secure main grounds for the PCM to ensure proper functionality. |
Car Diagnostics Training
- Car Electrical basics
- OBD-II scanner basics
- How to use an OBD reader
- Introduction to a Bi-directional Scan tool
- OBD scanner buyer’s guide + discounts