ECM-902A, ECM-902B, ECM-903F Volvo – ETM Throttle Motor & Limp Mode Diagnostic Guide

Diagnostic Priority: High

Complexity Level: Advanced

Technical diagnostic guide for Volvo P2 T5 / 2.4T / 2.5T covering DTCs ECM-902A, ECM-902B, ECM-903F. Factory measurement tolerances and 1:1 Cloning solutions.

Vehicle

VOLVO

Codes

3 units

Analysis Type

Technical Expert

Status

Analyzed

Technical Analysis

REF: #272808

The fault code combination ECM-902A, ECM-902B, ECM-903F on Volvo P2 T5 / 2.4T / 2.5T points to a validated mechanical or sensor failure requiring systematic diagnostic verification.

Expected Symptoms

Vehicle enters Limp Home mode with severely restricted throttle response (DTCs: ECM-902A, ECM-902B, ECM-903F)

Hunting/surging idle speed between 600 and 1,400 RPM or engine stalling when coming to a stop

ETS or Check Engine warning illuminated during heavy acceleration

System Impact

Drivetrain

Engine Control

Emission Control

Potential Fault Sources

01Worn resistive carbon wiper tracks on internal throttle potentiometers (Magneti Marelli) (affecting circuit for ECM-902A, ECM-902B, ECM-903F)

02Heavy carbon and oil sludge buildup around throttle plate causing mechanical binding

03Failing internal drive motor or voltage drop to throttle body electronics (logged fault: ECM-902A)

Workflow / Methodology

Verify supply voltage and reference ground for ECM-902A, ECM-902B, ECM-903F with multimeter at key ON.

Measure TPS Potentiometer 1 and 2 signals with oscilloscope; sum must strictly equal 5.0 V ± 0.1 V.

Inspect throttle bore cleanliness and remove carbon deposits around the butterfly plate.

Upgrade to contactless throttle body or 1:1 ETM module refurbishment at OBD Tuning.

Live Data & Mätvärdestoleranser (Är/Bör-värden)

Fabriksgodkända referensvärden vid diagnos och live-avläsning

Mätvärdesblock

Parameter / Signal	Testvillkor	Bör-värde (Normalt)	Avvikelse / Varning
ETM Motorström	Reglering	0.8 – 2.2 A	> 4.0 A (Kärvande spjäll)
Potentiometersumma TPS1 + TPS2	Hela spjällrörelsen	5.00 V ± 0.10 V	Avvikelse > 0.25 V
Spjällvinkel Tomgång	Varm motor 800 rpm	2.5 – 4.2 %	> 7.5 % (Koksbelagt spjäll)

Assessment & Action Proposal

Technical Recommendation

Replacement of gasspjällshus och inspection of Klämma 30 spänningsmatning till spjällrelä.

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Vanliga frågor om dessa felkoder

Vad är den primära orsaken till felkoderna?

The fault code combination ECM-902A, ECM-902B, ECM-903F on Volvo P2 T5 / 2.4T / 2.5T points to a validated mechanical or sensor failure requiring systematic diagnostic verification.

Kan man köra vidare med tänd motorlampa / varningslampa?

Körning med aktiva felkoder kan leda till strypt motoreffekt (nödläge / Limp Home), blockerad partikelfilterregenerering eller följdskador på mekaniska komponenter. Felsökning bör genomföras omgående.

Hur åtgärdas kombinationen på säkrast sätt?

Replacement of gasspjällshus och inspection of Klämma 30 spänningsmatning till spjällrelä.