Emissions / AuxiliaryLow ImpactDiesel

P0404 — Diagnostic Trouble Code P0404

OBD-II diagnostic code P0404 relates to the emissions / auxiliary system. This code is logged when the ECU detects a parameter outside its expected operating range.

4+

Affected Brands

7+

ECU Platforms

2

Related Services

6

Related DTCs

Symptoms

What the driver typically experiences when P0404 is stored

!Check Engine Light
iFailed emissions test
iNo major drivability impact

Why does P0404 appear after tuning?

This code may appear after ECU modifications when the affected system monitoring has not been fully recalibrated for the new operating parameters.

How proper calibration can address P0404

WEREMAP professional calibrations include comprehensive diagnostic management for all affected systems, preventing unnecessary fault codes while maintaining safe operation.

Related Tuning Services

Relevant services for the system behind P0404

EGR OffDTC Off

Related Diagnostic Codes

Codes from the same diagnostic system as P0404

P0401Low Impact

Exhaust Gas Recirculation (EGR) Flow Insufficient

P0409Low Impact

Diagnostic Trouble Code P0409

P0101Moderate Impact

Mass Air Flow (MAF) Sensor Range/Performance

P0400Low Impact

Exhaust Gas Recirculation Flow

P0402Low Impact

Diagnostic Trouble Code P0402

P0403Low Impact

Exhaust Gas Recirculation (EGR) Control Circuit

Affected ECU Platforms

Bosch EDC16C34Bosch EDC16CP31Bosch EDC17C66Bosch EDC17C57Bosch EDC16C31Bosch BOSCH EDC16 edc16c39Siemens/Continental SID20X

Commonly Affected Vehicles

MBVitoBosch EDC17C66
HyundaiTucsonBosch EDC17C57
MBSprinter215/315/415/515Bosch EDC16C31
FordFocusBosch EDC16C34
JeepGrand CherokeeBosch EDC16CP31

Based on data from 4+ vehicle brands. P0404 is not limited to these models.

Frequently Asked Questions

What does P0404 mean?â–¼
OBD-II diagnostic code P0404 relates to the emissions / auxiliary system. This code is logged when the ECU detects a parameter outside its expected operating range.
Why does P0404 appear after ECU tuning?â–¼
This code may appear after ECU modifications when the affected system monitoring has not been fully recalibrated for the new operating parameters.
How do you prevent P0404 during remapping?â–¼
WEREMAP professional calibrations include comprehensive diagnostic management for all affected systems, preventing unnecessary fault codes while maintaining safe operation.
Which vehicles are affected by P0404?â–¼
P0404 is commonly found on MB, Hyundai, Ford, Jeep vehicles equipped with Bosch EDC16C34, Bosch EDC16CP31, Bosch EDC17C66, Bosch EDC17C57 ECU platforms.
What other codes appear alongside P0404?â–¼
P0404 frequently appears together with P0401, P0409, P0101, P0400, P0402. These related codes typically originate from the same system modification and should be addressed together in the calibration.

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