OBD Guide
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P0604

Internal Control Module Random Access Memory (RAM) Error

P0604 is an OBD-II diagnostic trouble code meaning: Internal Control Module Random Access Memory (RAM) Error. Common causes: internal hardware defect of the ram chip in the ecu, unstable or low ecu supply voltage. Estimated repair cost: $33–278.

Severity
🔴 High
Can you drive?
Do not drive — repair immediately
Approx. repair cost
$33–278 (est.)

Symptoms

  • The Check Engine light comes on
  • The engine goes into limp mode
  • Unstable engine operation, jerking and failures
  • Random reset of ECU settings and adaptations
  • Possible difficulty starting or starting failure

Causes

  • Internal hardware defect of the RAM chip in the ECU
  • Unstable or low ECU supply voltage
  • Oxidation or damage to the ECU connector
  • Voltage surge in the on-board network
  • ECU software failure (requires reprogramming)

How to Fix

  1. Check battery voltage and generator charging (normal 13.8–14.4 V)
  2. Inspect and clean the ECU connector, check the reliability of the connection
  3. Check the fuses and relays of the ECU power supply circuit
  4. Reset the error, perform a test drive, check for the reappearance of the code
  5. If the error repeats, diagnose the ECU on a bench or replace/reprogram the control unit

Related codes

P0605P0606P0607P0600

Error P0604 by Vehicle Brand

AcuraAudiBAICBMWBYDBuickCadillacChanganCheryChevroletChryslerCitroenDodgeDongfengExeedFAWFordForthingFotonGACGMGMCGeelyGreat WallHavalHondaHongqiHyundaiInfinitiJACJaecooJaguarJeepJetourKaiyiKiaLadaLexusLi AutoLifanLincolnLivanMazdaMercedes-BenzMercuryMitsubishiNIONissanOldsmobileOmodaOpelPeugeotPlymouthPontiacRenaultSWMSaturnSkodaSkywellSubaruSuzukiTankToyotaVolkswagenVolvoVoyahXPengZeekrZotye

FAQ

What does the P0604 code mean?

P0604 is an OBD-II diagnostic trouble code that indicates: Internal Control Module Random Access Memory (RAM) Error

What causes a P0604 error code?

The most common causes of P0604 include: Internal hardware defect of the RAM chip in the ECU; Unstable or low ECU supply voltage; Oxidation or damage to the ECU connector; Voltage surge in the on-board network.

How do I fix a P0604 diagnostic trouble code?

To fix P0604: Check battery voltage and generator charging (normal 13.8–14.4 V). Inspect and clean the ECU connector, check the reliability of the connection. Check the fuses and relays of the ECU power supply circuit. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P0604?

Do not drive — repair immediately

How much does it cost to fix P0604?

The estimated repair cost for P0604 is $33–278. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat