Chevy Silverado 1500 P0606 — PCM Processor Internal Fault

Chevrolet-specific code — factory diagnostic data

Last updated: May 14, 2026

Definition source: Chevrolet factory description. Diagnostic guidance is based on factory-defined fault logic for this code.

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↗Looking for the cross-vehicle definition? Read the generic P0606 article for the SAE-defined fault logic that applies to all manufacturers.

P0606 Quick Answer

P0606 on a Silverado means the PCM has detected an internal processor fault during a self-check. Before condemning the PCM ($600-$1,400 part), rule out the cheaper causes that mimic this code: a low-voltage condition (B1325 partner code), a poor PCM ground, and a software issue resolved by a TSB-specified reflash. Genuine PCM failure is the LEAST common cause.

What Does P0606 Mean on a Chevy Silverado 1500?

The Chevrolet Silverado 1500 (2007-2019) stores P0606 when the condition described above is met. This guide focuses on the All configurations. Diagnostic priorities and likely root causes differ from the generic SAE definition because of platform-specific failure patterns documented below.

Symptoms

• Check Engine Light (P0606)
• Possibly multiple unrelated codes stored
• Truck may go into “limp” mode (reduced power)
• Possible no-start or hard-start condition
• Erratic behavior — intermittent stalls, surges, electronic dash glitches

Common Causes (Most Likely on This Model First)

1. Low system voltage during self-test. The PCM’s internal self-check fails if voltage drops below threshold. Often paired with B1325. Fix the battery / charging system first — P0606 may clear automatically.
2. PCM ground corrosion. The PCM bolts to the inner fender. Corroded mounting bolts or a poor ground strap can cause intermittent processor faults. Inspect and clean.
3. Required software / calibration update. GM has issued PCM reflash TSBs for various year/engine combos. Dealer scan tool checks for an updated calibration.
4. Damaged PCM connector pins. Heat damage, backed-out pins, or water ingress at the PCM connectors. Inspect both connectors for pin damage and green corrosion.
5. Genuine PCM internal failure. Only after the above checks. Replacement requires programming with VIN-specific calibration at a dealer or capable indie shop.

Diagnostic Approach

1. Read ALL stored codes — if B1325 (low voltage) or U-codes (lost communication) are also stored, fix charging system first.
2. Check battery voltage and charging system output. Charge / replace battery if voltage low.
3. Inspect the PCM ground strap and mounting points. Clean any corrosion.
4. Inspect PCM connectors for damaged pins or moisture. The PCM is mounted in a relatively protected location but moisture intrusion does happen.
5. Have a dealer or capable shop check for a current calibration. A reflash often resolves P0606.
6. Only as a last resort: replace the PCM and have it programmed to the truck’s VIN.

Possible Fixes

Can I Still Drive With P0606?

It depends on driveability. If the truck runs normally and only the CEL is on, drive briefly to a shop. If the truck is in limp mode or stalling, get it towed — sustained operation with a failing PCM can leave you stranded at any moment.

How Serious Is This Code?

Moderate to high. The code itself is rare and serious enough that diagnostic time at a dealer is worth the cost compared to a parts-cannon approach.

Repair Costs