P0604

Code

SEAT P — Powertrain

PCM RAM memory - fault

Brand: SEAT

Type: P — Powertrain

Views: UK: 8 EN: 19 RU: 10

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Intermittent or low battery voltage
Poor or corroded power/ground connections to PCM
Blown PCM fuse or fusible link
PCM water ingress or physical damage
Software corruption or failed firmware update
Electrical transients (voltage spikes) or short to power/ground

Symptoms

MIL/Check Engine lamp illuminated
Intermittent drivability issues (stall, rough idle, reduced performance)
No-start condition or crank but no start
Stored multiple PCM-related DTCs and communication errors
Unexpected limp mode or reduced functionality of engine controls
Erratic or lost communication with scan tool/ECM

What to check

Read all stored and pending codes and note freeze frame data
Check battery resting voltage and voltage during cranking and when engine running
Scan for communication errors on CAN/diagnostic bus
Inspect PCM power and ground fuses/relays and verify continuity
Visually inspect PCM connectors and wiring for corrosion, bent pins, water, or damage
Perform voltage drop test on PCM power and ground circuits with harness connected

Signal parameters

Battery voltage (key ON, engine OFF) — typically 12.4–12.8 V minimum
Cranking voltage — typically should not fall below ~9.6 V (vehicle-specific)
Supply voltage at PCM power pins (key ON and cranking)
Ground circuit voltage drop (should be low,
CAN bus activity/state when read with scan tool
Freeze frame: vehicle conditions when code set (voltage, rpm, temperature)

Diagnostic algorithm

Connect a capable scan tool; record all DTCs, freeze frame, and PCM communication/status info
Clear codes and attempt to reproduce; note whether P0604 returns immediately or under specific conditions
Verify battery state-of-charge and perform a battery/charging system load test; replace weak battery before proceeding
Inspect and secure all PCM power and ground connections; remove connector and inspect pins, apply dielectric if required
Measure voltage at PCM power/ground pins (key ON, cranking, engine running) and perform voltage-drop tests on wiring to chassis ground and battery positive
Inspect wiring harness for damage, chafing or water entry, especially near firewall and underbody routing
Check for other DTCs that point to supply faults (fuses, relays); replace any blown fuses and retest
If wiring and supply are good, check for recent software updates or interruptions; attempt a reflash/update with the manufacturer’s tooling per service procedure
If reflash fails or faults persist after verifying power/grounds and software, follow manufacturer procedure for PCM reprogram/replace. Replacing PCM commonly requires VIN programming and immobilizer re-synchronization
After repair/reprogramming, clear codes and perform a full road test and final scan to ensure P0604 does not return

Likely causes

Low battery voltage or weak battery under load
Loose/poor PCM ground or power connector
Corroded PCM connector pins or harness damage at PCM
Previous unsuccessful PCM reflash or interrupted update
Water intrusion at PCM connector or housing

Fault status

⚠️ Status

P0604 — PCM RAM memory fault. The powertrain control module detected an internal RAM error during self-test. Investigate battery/charging, power and ground, connector condition, recent programming events and PCM integrity.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 2-4 hours

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P0604 — PCM RAM memory - fault