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P1604

Code Word Unregestered

P1604 is described as “Code Word Unregestered” in the Generic OBD2 reference. Other reference families are shown below; select the scope relevant to your vehicle.

Manufacturer reference family

BMW: P1604

en

Control Module Self Test, Speed Monitoring; Control Module Self-Test, Speed Monitoring

Reference namespace
bmw
Source revision
legacy-oem-dtc-r2-20260924

Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.

Related catalog brands: BMW.

10 profiles assigned this reference family
Manufacturer reference family

Chrysler: P1604

en

PCM Internal Dual-Port RAM Read/Write Integrity Failure

tr

PCM Dahili Çift Bağlantı Noktalı RAM Okuma / Yazma Bütünlük Hatası

Reference namespace
chrysler
Source revision
legacy-oem-dtc-r2-20260924

Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.

Related catalog brands: Chrysler.

5 profiles assigned this reference family
Manufacturer reference family

Continental Synerject Easy U: P1604

en

ECU Internal Warm Restart Failure

Reference namespace
continental-synerject-easy-u
Source revision
legacy-oem-dtc-r2-20260924

Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.

Manufacturer reference family

Dodge / Fiat: P1604

en

Main relay

Reference namespace
fiat
Source revision
legacy-oem-dtc-r2-20260924

Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.

Related catalog brands: Fiat, Dodge.

27 profiles assigned this reference family

3 more related profiles are listed in the vehicle directory.

Manufacturer reference family

Ford: P1604

en

Code Word Unregestered

Reference namespace
ford
Source revision
legacy-oem-dtc-r2-20260924

Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.

Related catalog brands: Ford.

28 profiles assigned this reference family

4 more related profiles are listed in the vehicle directory.

Manufacturer reference family

GM: P1604

en

Loss Of IPC Serial Data; Loss of IPC Serial Data

Reference namespace
gm
Source revision
legacy-oem-dtc-r2-20260924

Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.

Manufacturer reference family

Genesis / Hyundai / Kia: P1604

en

No ID From ECU

Reference namespace
hyundai-kia
Source revision
legacy-oem-dtc-r2-20260924

Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.

Related catalog brands: Kia, Genesis, Hyundai.

401 profiles assigned this reference family

377 more related profiles are listed in the vehicle directory.

Manufacturer reference family

Mazda: P1604

en

Immobilizer System Fault

Reference namespace
mazda
Source revision
legacy-oem-dtc-r2-20260924

Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.

Related catalog brands: Mazda.

7 profiles assigned this reference family
Manufacturer reference family

Mercedes-Benz: P1604

en

Code Word Unregistered

Reference namespace
mercedes-benz
Source revision
legacy-oem-dtc-r2-20260924

Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.

Related catalog brands: Mercedes-Benz.

13 profiles assigned this reference family
Manufacturer reference family

Dodge / Mitsubishi: P1604

en

Code Word Unregestered; Chassis No. not programmed

Reference namespace
mitsubishi
Source revision
legacy-oem-dtc-r2-20260924

Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.

Related catalog brands: Mitsubishi, Dodge.

31 profiles assigned this reference family

7 more related profiles are listed in the vehicle directory.

Manufacturer reference family

Infiniti / Nissan: P1604

en

Code Word Unregestered

Reference namespace
nissan
Source revision
legacy-oem-dtc-r2-20260924

Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.

Related catalog brands: Nissan, Infiniti.

62 profiles assigned this reference family

38 more related profiles are listed in the vehicle directory.

Generic OBD2

Generic OBD2: P1604

en

Code Word Unregestered

Reference namespace
obd2
Source revision
legacy-2.2.20

Generic OBD2 definition; confirm the protocol and vehicle-specific service information.

Manufacturer reference family

Belgee / Geely / Proton: P1604

en

Code Word Unregestered

Reference namespace
proton
Source revision
legacy-oem-dtc-r2-20260924

Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.

Related catalog brands: Belgee, Geely, Proton.

5 profiles assigned this reference family
Manufacturer reference family

Dacia / Renault: P1604

ru

Замените блок управления C-002

Reference namespace
renault
Source revision
legacy-oem-dtc-r2-20260924

Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.

Related catalog brands: Dacia, Renault.

170 profiles assigned this reference family

146 more related profiles are listed in the vehicle directory.

Manufacturer reference family

Saab: P1604

en

Internal Control Module Malfunction

Reference namespace
saab
Source revision
legacy-oem-dtc-r2-20260924

Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.

Manufacturer reference family

Chevrolet / Citroen / General Motors / Opel / Peugeot: P1604

en

Code word Unregistered

Reference namespace
stellantis-psa
Source revision
legacy-oem-dtc-r2-20260924

Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.

Related catalog brands: Chevrolet, Opel, Citroen, General Motors, Peugeot.

35 profiles assigned this reference family

11 more related profiles are listed in the vehicle directory.

Manufacturer reference family

Audi / Jetta / MAN / Seat / Skoda / Volkswagen: P1604

de

Loss of IPC Serial Data; Internal Control Module Driver Error

en

Loss of IPC Serial Data; Internal Control Module Driver Error

Reference namespace
vag
Source revision
legacy-oem-dtc-r2-20260924

Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.

Related catalog brands: Skoda, Volkswagen, Audi, Seat, MAN, Jetta.

56 profiles assigned this reference family

32 more related profiles are listed in the vehicle directory.

Manufacturer reference family

Polestar / Volvo: P1604

en

Internal Control Module Driver Error

Reference namespace
volvo
Source revision
legacy-oem-dtc-r2-20260924

Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.

Related catalog brands: Polestar, Volvo.

12 profiles assigned this reference family

What should I check before using this definition?

Keep the full code, module, status and freeze-frame data. Confirm the vehicle’s make, model, year and current manufacturer service information before choosing a repair. This entry does not identify a failed part by itself.

Organize a scan report or recording
Source and applicability

OBD Lens production library legacy-owner-2026-10-09-v81. This is a scoped technical reference, not a scan of your car. A catalog relationship does not certify that every ECU, year or engine returns the same signal or code definition.

Read the reference method

OBD Lens reference library · catalog legacy-owner-2026-10-09-v81. Sources and scope