P0600 — Serial Communication Link

Q: Does the ECM really need replacement?

Rarely. Less than 10% of P06xx codes need ECM replacement. Most are power supply issues, software glitches, or water intrusion.

Q: Can I use a junkyard ECM?

Must be reprogrammed to your VIN and immobilizer. Remanufactured pre-programmed units are better.

Q: Can a dead battery cause ECM codes?

Absolutely. Voltage below 10V during cranking corrupts ECM memory and triggers internal fault codes.

What Does P0600 Mean?

P0600 is a diagnostic trouble code indicating: Serial Communication Link. This code relates to the computer and output circuits system. It has been reported in NHTSA complaints across 3 different vehicle models.

The Engine Control Module (ECM) or Powertrain Control Module (PCM) is the central computer managing all engine functions. It processes data from dozens of sensors and controls fuel injectors, ignition coils, VVT solenoids, EGR, EVAP purge, and more. P06xx codes indicate problems within the ECM itself or its internal circuits — these can affect multiple systems simultaneously. Common causes include voltage supply problems (low battery, bad alternator, corroded grounds), software glitches requiring reflash, water intrusion, or genuine internal ECM failure. Before condemning the ECM, ALWAYS verify power, ground, and reference voltage circuits — 90% of suspected ECM failures are wiring or power supply issues. ECM replacement is expensive ($500-$2000+) and requires VIN-specific programming.

Symptoms of P0600

⚠️ Check engine light (possibly multiple warning lights)
⚠️ Multiple unrelated codes stored simultaneously
⚠️ Intermittent no-start or stalling
⚠️ Erratic engine behavior
⚠️ Loss of specific functions (A/C, fans, etc.)
⚠️ Vehicle may enter limp mode

Common Causes

🔍 Low battery voltage or failing alternator
🔍 Corroded or loose ECM ground connections
🔍 Water intrusion into ECM housing
🔍 ECM software requiring reflash/update
🔍 Internal ECM component failure

P0600 Reports by Year

2022

1

2015

1

2024

1

Real Owner Reports

From NHTSA complaint database — actual owner descriptions.

"Three months into purchasing a brand new 2019 Honda Odyssey EX-L my car would not start. I was told my battery was drained/bad cell, due to the weather being too cold and all the electrical components of my vehicle. We lived in South Georgia and my van is kept in a garage. I was given a new battery "
— Honda Odyssey owner, 09/28/2022

"AT 5,500 MILES, WHEN I WOULD ACCELERATE INTO TRAFFIC, I WOULD LOSE POWER TO MY PEDAL. MY PEDAL WOULD BE NON RESPONSIVE FOR UP TO 40 SECONDS WHEN THE ENGINE LIGHT WOULD COME ON. AFTER ABOUT 40 SECONDS, IT COULD COME ALIVE AND CATCH, BUT BY THEN, I AM IN DANGER BECAUSE THE CAR BEHIND ME THINKS I'VE A"
— Dodge Charger owner, 06/05/2015

"The contact owns a 2019 Mercedes-Benz C300. The contact stated that the "Service Engine Soon" warning light was illuminated. The contact restarted the vehicle several times; however, the warning light remained illuminated. The vehicle was taken to an independent mechanic who retrieved DTC code: P060"
— Mercedes-Benz C-Class owner, 11/08/2024

Source: NHTSA Complaints Database

Most Reported Vehicles for P0600

Based on NHTSA owner complaint data.

#	Vehicle	Reports
1	HONDA ODYSSEY
2	DODGE CHARGER
3	MERCEDES-BENZ C-CLASS

Diagnostic Tips

CHECK BATTERY VOLTAGE FIRST — weak battery causes most P06xx codes
Inspect ALL ECM ground connections with voltage drop test (<0.1V)
Check ECM connector for corrosion, bent pins, water intrusion
Check for manufacturer TSBs — many have known software updates

Common Mistakes to Avoid

❌ Replacing ECM without checking power/ground circuits — $500-$2000 mistake
❌ Using junkyard ECM without reprogramming
❌ Ignoring weak battery as root cause

Frequently Asked Questions

Does the ECM really need replacement?