P0606 on a 2017 GMC Sierra 1500

PCM Internal Processor Fault

P0606 on a 2017 GMC Sierra 1500 indicates pcm internal processor fault. Stop driving and diagnose it before continuing — it can signal an unsafe condition. The most common cause is low battery voltage or weak battery causing pcm brown-out (typically $100–$350). Confirm the root cause before replacing parts.

Severity: high Do not drive Pickup Truck 2015-2019 GMC Sierra 1500

Reviewed by MECH AI Editorial · Last verified May 25, 2026

What does P0606 mean on a 2017 GMC Sierra 1500?

P0606 is set when the engine control module's internal self-test detects an inconsistency in its own processor — typically a RAM test, ROM checksum, watchdog timeout, or processor brown-out. Unlike most OBD-II codes which point to an external sensor or actuator, P0606 is the PCM saying "something is wrong with me." The cause is usually a power or ground issue, water intrusion, or the PCM itself failing.

This guide covers P0606 across the 2015-2019 GMC Sierra 1500 generation — the symptoms, causes, and diagnostic steps below apply to every model year from 2015 through 2019.

Is it safe to drive a 2017 GMC Sierra 1500 with P0606?

No. P0606 is a high-severity code on the 2017 GMC Sierra 1500 — avoid driving until it is diagnosed and repaired, as it can indicate an unsafe condition or risk further damage.

What are the symptoms of P0606 on a 2017 GMC Sierra 1500?

Check Engine Light is illuminated
Reduced engine power / limp mode
Erratic or random drivability issues
Multiple unrelated codes setting simultaneously
Hard starting or no-start
Loss of communication with scan tool intermittently
Random stalling

What causes P0606 on a 2017 GMC Sierra 1500?

Cause	Likelihood	Estimated repair (USD)
Low battery voltage or weak battery causing PCM brown-out Always test battery and charging before condemning the PCM.	Most common	$100–$350
Corroded or loose PCM power / ground connection	Common	$50–$250
Water intrusion into the PCM enclosure	Common	$400–$1,500
Failed PCM module (internal electronics)	Common	$500–$1,500
Failed alternator producing dirty / noisy charging voltage	Occasional	$200–$700
Software corruption requiring reflash	Occasional	$100–$400

How to diagnose this on a 2017 GMC Sierra 1500

Test the battery and charging system FIRST

P0606 from low voltage is the most common cause and the cheapest fix. A battery weaker than 12.4 V at rest, or charging voltage below 13.5 V at idle, can brown out the PCM and set P0606. Replace the battery or repair the alternator before touching the PCM.

Tools: Multimeter, Battery load tester
Check PCM power and ground connections

Locate the PCM (typically under the hood near the firewall, or under the dash). Inspect every connector for corrosion, bent pins, or water damage. Verify all ground straps from the engine and PCM are tight to clean bare metal. Loose grounds cause classic intermittent P0606.

Tools: Multimeter, Wire brush, Electrical contact cleaner
Inspect the PCM for water intrusion

Remove the PCM and inspect the case seam, connector seals, and the PCB visible through any vents. Green corrosion on the board confirms water damage — replacement is the only fix at that point. Common entry points: cowl drain blockage, rear-vent seal failure, or aftermarket sunroof drain issues.

Tools: Socket set, Inspection light
Read all codes from all modules

P0606 alone is one thing; P0606 with codes from 3+ other modules (TCM, ABS, BCM) usually points at a shared cause like low system voltage. Pull codes from every module before deciding the PCM is the problem.

Tools: Scan tool with multi-module access
Try a PCM reflash before replacement

Sometimes P0606 is caused by software corruption — particularly after a battery disconnect or jump-start with reversed polarity. A dealer or independent shop with the correct programming software can attempt a reflash for a fraction of the replacement cost.

Tools: OEM scan tool or J2534 reprogramming setup

NHTSA complaints & recalls for the 2017 GMC Sierra 1500

Owner-reported safety complaints and official recalls filed with the U.S. National Highway Traffic Safety Administration for the 2017 GMC Sierra 1500. Use these to gauge how common a problem is on your specific vehicle before you start chasing GMC Sierra 1500 diagnostics.

425 owner complaints

20 involved a crash

5 involved a fire

8 reported injuries

POWER TRAIN 142
ENGINE 62
SERVICE BRAKES 127
ELECTRICAL SYSTEM 60
UNKNOWN OR OTHER 41

5 active recalls

SERVICE BRAKES, HYDRAULIC:POWER ASSIST:VACUUM Sep 2019

General Motors LLC (GM) is recalling certain 2015-2017 Cadillac Escalade, 2014-2018 Chevrolet Silverado, GMC Sierra, 2015-2018 Chevrolet Suburban, Tahoe, GMC Yukon vehicles. The amount of vacuum created by the vacuum pump may decrease over time.…
NHTSA campaign 19V645000
SERVICE BRAKES, HYDRAULIC:ANTILOCK/TRACTION CONTROL/ELECTRONIC LIMITED SLIP:WHEEL SPEED SENSOR/TONE RING Oct 2019

General Motors LLC (GM) is recalling certain 2015-2020 Chevrolet Suburban, Tahoe, and GMC Yukon, and 2014-2018 Chevrolet Silverado 1500 and GMC Sierra 1500 vehicles equipped with a 5.3-liter engine, a 3.08-ratio rear axle and four-wheel drive. If a wheel-speed sensor fails, whil…
NHTSA campaign 19V761000
AIR BAGS:FRONTAL Sep 2016

General Motors LLC (GM) is recalling certain model year 2015-2017 Chevrolet Silverado 2500 HD, 3500 HD, Tahoe, Suburban, GMC Sierra 2500 HD and 3500 HD, GMC Yukon, GMC Yukon XL, Cadillac Escalade and Cadillac Escalade ESV vehicles and 2014-2017 Chevrolet Corvette, Silverado 1500…
NHTSA campaign 16V651000
CHILD SEAT:TETHER: CONNECTOR/CLIP Aug 2017

General Motors LLC (GM) is recalling certain 2017 Chevrolet Silverado 1500, and GMC Sierra 1500 trucks. The owner's manual for the affected vehicles may be missing instructions on how to use the tether anchorage and child restraint anchorage systems. As such, these vehicles fai…
NHTSA campaign 17V487000

How do I fix P0606 on a 2017 GMC Sierra 1500?

Replace the battery and / or alternator
Clean and re-tighten all PCM power and ground connections
Repair water intrusion source and replace the PCM
Replace the PCM with a programmed unit
Reflash the PCM software

About the 2015-2019 GMC Sierra 1500

The 2015-2019 GMC Sierra 1500 was commonly sold with the following powertrains: 5.3L V8, 6.2L V8, 2.7L Turbo I4, 3.0L Duramax I6 Diesel. Common trims include Pro, SLE, Elevation, SLT, AT4, Denali.

Why a weak battery sets P0606

Modern engine control modules require stable voltage to run their internal self-tests. When voltage dips below approximately 9 V during a crank — even briefly — the PCM may reset, fail an internal check, and store P0606 as evidence of the brown-out. This is so common that “load-test the battery” is always the first diagnostic step. Replacing a $120 battery has resolved more P0606 codes than any other single repair.

Water intrusion and the cowl drain

A clogged cowl drain (the drain that lets rainwater out from under the windshield wipers) can let water pool against the firewall — directly above where many vehicles mount the PCM. Over time water wicks into the connector and corrodes the board. Always check the cowl drain when investigating P0606, especially on vehicles parked outdoors and on those with visible water staining inside the cabin.

PCM replacement is the last resort

A PCM costs $400–$1,500 and must usually be programmed and keyed to the vehicle before it will run. Try every cheaper cause first:

Battery and charging system test
Power and ground connection inspection
Multi-module code scan
Software reflash

Only after all of those fail should the PCM itself be condemned. Refurbished and remanufactured PCMs are available at 30–50 % of new prices and are sometimes a better choice on older vehicles.