OBD-II DIESEL WERKSTATTPROTOKOLL8-10 min read
P2453DPF & AbgasreinigungHohe Dringlichkeit💡 Motorkontrollleuchte an

P2453: Dieselpartikelfilter (DPF) Differenzdrucksensor 'A' - Bereichs-/Funktionsfehler (Signal unplausibel)

Der Diagnose-Fehlercode (DTC) P2453 weist darauf hin, dass das Motorsteuergerät (EDC/MSG) einen Plausibilitäts-, Messbereichs- oder dynamischen Korrelationsfehler im Signal des Dieselpartikelfilter-Differenzdrucksensors 'A' festgestellt hat. Im Gegensatz zu einem Kurzschluss oder einer Leitungsunterbrechung wird P2453 gesetzt, wenn der Sensor eine elektrisch valide Signalspannung liefert, der resultierende Differenzdruckwert jedoch im Widerspruch zur realen Abgasströmungsdynamik steht. Typische Auslösebedingungen sind: (1) Nullpunkt-Offset-Drift bei Zündung EIN und Motor AUS (Sensor meldet Druck ohne Abgasmassenstrom); (2) Sensorwert bleibt statisch oder reagiert träge bei dynamischen Lastwechseln unter Volllast; (3) Negativer Differenzdruck infolge vertauschter Druckentnahmeleitungen; oder (4) Gerissene bzw. undichte Druckschläuche mit Abblasen gegen Umgebungsdruck.

🚗 FAHRER-HILFE & REPARATUR-LEITFADEN

🚗 Fahrsicherheit, typische Reparaturkosten & Diagnose-Prüfung

🟡 Achtung: Notlauf aktiv / Zeitnah Werkstatt aufsuchen
  1. 01

    🚦 Fahrsicherheit & Betriebsrisiko

    Sofortige mechanische Bewertung und Abschlepp-Empfehlung

    DPF-Differenzdrucksensor 'A' Schaltkreis Bereich/Funktion - Sensorsignaldrift

    Der Differenzdrucksensor meldet unplausible Druckwerte (z. B. negativen Differenzdruck oder unveränderte Werte beim Gasgeben). Die interne piezoresistive Messmembran ist dekalibriert.

    MECHANISCHE RISIKEN & MOTORSCHÄDEN BEI WEITERFAHRT:Unzuverlässige Rußmassenermittlung führt entweder zu unnötig häufigen Regenerationen (Ölverdünnung) oder zur Verstopfung des DPF.
  2. 02

    💰 Typisches Werkstatt-Budget

    Erwartete Kostenstufen für Teileaustausch und Werkstattarbeit
    Kleinere Wartung / Filterspülung35 € - 80 €: Ruß aus Druckleitungen entfernen und Nullpunktabgleich per Diagnosetester durchführen

    Sensorreinigung, Kraftstofffilterwechsel, Sicherungsprüfung oder Steckerkontaktreinigung.

    Ventil- / Sensor-Austausch90 € - 240 €: Einbau eines neuen Original-DPF-Differenzdrucksensors

    Austausch von Einzelkomponenten (z. B. Druckbegrenzungsventil, Zumesseinheit oder instandgesetzter Injektor).

    Generalüberholung / Pumpe & Injektoren750 € - 2.200 €: Professionelle DPF-Reinigung im ausgebauten Zustand oder Filterelement-Austausch

    Überholung der Hochdruckpumpe, neuer OEM-Injektorsatz oder Austausch der DPF-Baugruppe.

    Werkstatt-Richtwerte. Daten belegen, dass über 70% der Fälle in Stufe 1 oder 2 ohne Tausch kompletter Baugruppen behoben werden.

  3. 03

    🧰 Schnelle Sicht- & Funktionsprüfung vor Ort

    5-Minuten-Garagen-Schnellcheck ohne Spezialwerkzeug
    11. Live-Druckdaten bei Zündung EIN und Motor AUS auslesen: Der Differenzdruck muss zwischen -3 und +3 mbar liegen (Werte über 30 mbar deuten auf Sensordefekt hin).
    22. Motor auf 2.500 U/min drehen: Der Druck sollte je nach Rußbeladung gleichmäßig auf 30-80 mbar ansteigen.
    33. Silikonschläuche zwischen Abgasrohr und Sensorgehäuse auf Risse oder Knicke prüfen.
  4. 04

    🛡️ Schutz vor Fehldiagnosen (Mechanic Shield)

    Gezielte Fachfragen an die Werkstatt zur Vermeidung unnötiger Teilewechsel
    ""Live-Werte des DPF-Differenzdrucks bei KOEO anzeigen; liegt der Wert bei stehendem Motor über 5 mbar, den Sensor erneuern.""
    ""Sicherstellen, dass der neue Sensor mit der Tester-Routine 'Anpassung Differenzdrucksensor' kalibriert wird.""
    ""Motorölstand auf Diesel-Ölverdünnung durch abgebrochene DPF-Regenerationszyklen prüfen.""

    Technischer Hinweis: Stellen Sie diese konkreten Fragen Ihrer Werkstatt, bevor Sie teure Baugruppen freigeben:

🔧 FACHPERSONAL-BERATUNG & WERKSTATT-PROTOKOLLRAPID ASSESSMENT

30-Sekunden Werkstatt-Triage

Hauptsymptome
  • Check Engine Light (MIL) illuminated continuously on the dashboard
  • Flashing DPF warning icon or 'Exhaust Filter Fault' message in the driver information center
  • Engine enters Limp-Home mode with sluggish throttle response and power capped below 3,000 RPM
Häufigste Ursachen
  • Cracked, burned through, melted, or detached rubber pressure sampling hoses between DPF and sensor
  • Pressure sampling hoses inadvertently reversed during previous DPF or transmission servicing
  • Zero-drift calibration shift in the sensor's piezoresistive silicon diaphragm due to thermal shock or aging
Erste Prüfmaßnahme

Connect scan tool live telemetry: compare Target Fuel Rail Pressure vs Actual Rail Pressure and log metering valve command PWM duty cycle during idle and road load.

Expensive Diagnostic Pitfall & Technical Reality

❌ Häufiger Werkstattirrtum:

P2453 confirms the DPF differential pressure sensor is broken and the DPF filter is hopelessly blocked, requiring a complete DPF replacement ($2,000 - $3,500).

🔍 Technische und hydraulische Realität:

P2453 is a rational performance plausibility DTC. The ECM runs automatic offset rationality checks: when the engine is turned off with the ignition on, the differential pressure MUST read precisely 0 mbar (atmospheric balance). If the sensor reads 15 mbar with the engine OFF, or if pressure fails to rise proportionally when revving the engine, P2453 is flagged. In 80% of vehicles, the sensor electronics are fine: the failure is caused by liquid water condensation freezing inside the rubber pressure hoses, a cracked sample line leaking to atmosphere, or the two pressure hoses being swapped backwards during a previous service.

💡 Technisches Prüfprotokoll:

Unnecessarily replacing the DPF canister ($2,200+) or blindly installing new sensors without blowing out clogged metal sample pipes ($150 sensor ruined again), when the true repair is clearing carbon soot from the steel sensor tubes ($0 - $45).

DPF Soot Overload & Thermal Runaway Meltdown Alert

CRITICAL WORKSHOP WARNING: Never ignore an active P2453 code or clear it repeatedly without diagnosing the cause!

MANDATORY PROTOCOL: When the ECM loses confidence in the differential pressure sensor circuit, it immediately locks out and aborts all automatic and active DPF regenerations to prevent uncontrolled soot fires. If the vehicle is driven under these conditions, carbon soot accumulates unchecked in the ceramic honeycomb. Once soot mass exceeds 45 grams, attempting a forced service regeneration creates an extreme thermal runaway (> 1,100°C) that melts the silicon carbide matrix, cracking the substrate and causing vehicle fire. Always verify physical soot load before forcing DPF regeneration.

PLATFORM ARCHITECTURE

Häufig betroffene Motoren & Einspritzplattformen

Dieser Fehlercode betrifft vorwiegend folgende Common-Rail-Dieselplattformen. Prüfen Sie unten Ihre Motorfamilie auf Werksfehlermuster, Baugruppenteilenummern und Reparaturlinks:

Volkswagen / Audi 2.0 TDI (EA189 / CFFB / CFGB)

Bosch EDC17 Common Rail System

Bekanntes Werksfehlermuster: Piezo stack degradation, injector harness terminal fretting, DPF differential pressure sensor silicone tube split.

Wichtige Unterbaugruppe:03L130277, 0445110369, 076906051A

BMW 2.0d / 3.0d (N47 / N57 / M57TU2)

Bosch CRI2.5 / CRI3.0 Common Rail

Bekanntes Werksfehlermuster: Injector balance drift beyond +/- 4.0 mg/stroke, glow plug control unit (BERU) power lead failure, DPF backpressure accumulation.

Wichtige Unterbaugruppe:13537805428, 0445116024, 12217801201

Ford 6.7L Powerstroke V8 Diesel

Bosch CP4.2 High-Pressure Common Rail System

Bekanntes Werksfehlermuster: EGR cooler carbon clogging, DEF injector white crust crystallization, fuel volume control valve harness chafing.

Wichtige Unterbaugruppe:BC3Z-9A543-A, FC3Z-9F593-B, BC3Z-5J281-A

Mercedes-Benz 2.1 CDI (OM651 / OM646)

Delphi CRD2 / Bosch Common Rail Injection

Bekanntes Werksfehlermuster: Delphi piezo to solenoid conversion wiring harness chafing, differential pressure sensor internal diaphragm drift.

Wichtige Unterbaugruppe:A6510704987, A6510700587, A0061539528
WORKSHOP MASTER TEARDOWN GUIDE

Diesel DPF Differential Pressure & Regeneration Guide

Workshop diagnostic guide for DPF fault codes P2452, P2453, P2454, P2455, P2458, and P2459. Delta-P sensor testing, hose routing, and regeneration troubleshooting.

Read Full Master Guide →
THEORY OF OPERATION

Steuerstromkreis & Aktorik-Logik

1. Dynamic In-Demand Fuel Metering

The DPF Differential Pressure Sensor measures the exhaust pressure drop across the ceramic filter matrix. Under fluid dynamic principles, the differential pressure (Delta-P) across a porous medium increases exponentially with volumetric exhaust flow rate (which is derived from engine RPM, intake MAF air mass, and exhaust temperature). The ECM compares measured Delta-P against an internal thermodynamic exhaust flow model. A healthy clean filter shows 5-25 mbar at idle and 70-150 mbar at full load.

2. Closed-Loop PID Deviation Monitoring

The ECM executes continuous rationality algorithms: (1) Static Zero Check: With Key-ON Engine-OFF, if measured Delta-P exceeds ±10 mbar (voltage outside 0.45V-0.55V) for > 3.0 seconds, zero-drift is flagged; (2) Dynamic Model Correlation: During wide-open throttle (WOT) acceleration where exhaust flow exceeds 300 kg/h, measured Delta-P must rise above 40 mbar. If Delta-P stays below 10 mbar (due to a split upstream hose), the ECM detects an implausible low-pressure state; (3) Negative Pressure Monitor: If the sensor outputs < -5 mbar (voltage < 0.42V) during driving, the hoses are reversed, triggering P2453.

3. Diagnostic Trap: Normally Open (NO) vs Normally Closed (NC) Valves

The Reversed Hose Diagnostic Rule: On many vehicles (e.g. Ford, VW, BMW), the two sampling hoses differ in diameter or length. If a technician swaps the upstream and downstream hoses during DPF servicing, the sensor measures a vacuum relative to the high-pressure side. Under acceleration, the voltage drops rather than rises, causing the ECM to log DTC P2453 within 500 meters of driving.

ENGINEERING SPECIFICATIONS

Elektrische & Hydraulische Prüfwerte

Solenoid Coil DC ResistancePiezoresistive Bridge Internal Resistance: 1.5 kΩ - 3.8 kΩ measured between 5V Ref and Ground pinsMeasured @ 20°C across terminals 1 & 2
Insulation Resistance> 10 MΩ measured between any sensor terminal pin and chassis ground (tested @ 250V/500V DC)Between terminals and pump body (ground)
Operating Supply VoltageECM Regulated 5V Reference Supply: 4.95 V - 5.05 V DC; Sensor Ground Return Drop: < 0.05 V DCHigh-side feed from ECM / main relay
PWM Frequency StandardLinear analog DC voltage (0.50V to 4.50V) proportional to differential pressure (0 to 100 kPa / 0 to 1,000 mbar)Square-wave PWM modulation
Idle Duty Cycle (Warm Engine)Clean Filter Output @ Idle (750 RPM, 0-25 mbar): 0.52 V - 0.70 V; KOEO Zero Reference (0 mbar): 0.48 V - 0.52 VNominal baseline at 250–350 bar
Full-Load Duty Cycle (WOT)Maximum Allowable Clean Differential Pressure @ 3,500 RPM Full Load: < 180 mbar (< 1.80V); Saturated DPF: > 350 mbarMaximum high-speed fuel delivery demand
Low-Pressure Feed SupplyMaximum Permissible Signal Wire Resistance: < 0.4 Ω end-to-end between ECM connector and sensor plugMeasured at pump fuel inlet
Internal Cascade BackpressureSampling Hose Burst Pressure: High-temp silicone lines rated for > 3.0 bar @ 250°C exhaust gas temperatureControlled by overflow cascade valve
PROCEDURAL PROTOCOL

Schritt-für-Schritt Werkstatt-Diagnoseprotokoll

STEP 1

Inspect Pressure Sampling Hoses for Burns, Splits, and Reversal

Visually examine the two pressure hoses connecting the DPF to the sensor. Check for burn-through holes, melting against the exhaust pipe, or kinked sections. Verify hose routing: the pipe coming from BEFORE the DPF ceramic core must connect to the High-Pressure (P1 / Upstream) nipple on the sensor. The pipe coming from AFTER the core (or open to atmosphere) must connect to the Low-Pressure (P2 / Downstream) nipple.

STEP 2

Key-ON Engine-OFF Zero-Pressure Calibration Test

With the engine OFF and ignition ON, connect a scan tool and read live DPF Differential Pressure. Healthy sensors must display 0 ± 5 mbar (voltage 0.48V-0.52V). If the scan tool indicates > 12 mbar (or < -5 mbar) with zero exhaust flow, disconnect both rubber hoses from the sensor. If the high reading persists with the nipples exposed to ambient air, the sensor is permanently zero-drifted and must be replaced.

STEP 3

Calibrated Mityvac Pressure Hand-Pump Bench Test

Connect a precision hand pressure pump (Mityvac) with an accurate digital gauge to the high-pressure port (P1) of the sensor. With ignition ON, pump to 50 mbar, 100 mbar, and 200 mbar. Observe the scan tool live pressure reading. The scan tool must display the applied pressure within ±5 mbar. If the reading is erratic, steps unevenly, or displays large hysteresis, replace the sensor.

STEP 4

Clear Metal Sampling Tubes with Compressed Air

Disconnect the rubber hoses at the sensor. Connect a blow gun with regulated compressed air (2.0 bar) to each metal pipe. Blow air backward into the DPF canister. You should hear air rushing freely through the exhaust. If resistance is met, the sampling pipe is plugged with hard soot or corrosion; ream with a flexible wire probe.

STEP 5

Dynamic Driving Pressure Verification

Reconnect hoses and perform a road test while graphing DPF Differential Pressure, Engine RPM, and MAF Airflow. Under wide-open throttle (WOT) in 3rd gear, differential pressure must climb smoothly with engine load (typically 80-180 mbar depending on soot loading). A reading that remains flat (< 10 mbar) or drops negative confirms a broken upstream hose or reversed connections.

STEP 6

DPF Ceramic Core Structural Integrity Inspection

If the sensor, hoses, and wiring are verified 100% sound, remove the downstream exhaust pipe or inspect with a borescope. If the DPF ceramic honeycomb has cracked, melted, or been hollowed out by a previous owner, exhaust gas flows through unrestricted, producing zero pressure drop and permanently triggering P2453.

COMPONENT-LEVEL REPAIR

Hardware-Instandsetzung & Komponenten-BOM

DPF Monolith Differential Pressure Pneumatic Sensing Circuit

Bosch Digital / Analog DPF Differential Pressure Sensor

0 281 006 005 / 0 281 006 278

High-sensitivity silicon diaphragm sensor measuring delta-pressure between inlet and outlet ports

OEM: Protocol: Replace if sensor output fails to reset to 0.50V ±0.03V during Key-On Engine-Off calibration
Steel Pre-DPF Pressure Sampling Pipe Tube with Heat Shielding

OEM Stainless Steel Exhaust Sampling Line

Routes high-temperature raw exhaust pressure pulses to the remote rubber sample hose

OEM: Protocol: Clean out using compressed air or steel guitar wire if plugged with hardened soot
Heat-Resistant Silicone Sample Hose Pair with Spring Tension Clamps

EPDM / Fluorosilicone Reinforced Hose Kit

Isolates engine vibration and temperature from reaching the plastic sensor body

OEM: Protocol: Replace if hoses show split ends, oil swelling, or hardening
Workshop Technical & Economic Benchmark: Steel pipe exhaust flare nuts: 35 - 45 Nm; Sensor mounting bracket 10mm bolt: 9 Nm; Handheld vacuum/pressure pump with 0-100 mbar calibration scale.
LIVE WORKSHOP TOOL

Live Common-Rail Toleranzrechner

DPF Pressure Differential Live Data Reference Table

Inspect live differential pressure vs engine state: Engine OFF: 0 mbar (±2 mbar max); Idle (800 RPM): 3 - 8 mbar; 2,500 RPM no load: 20 - 45 mbar; Max WOT: < 180 mbar.

📐 Factory Engineering Tolerance: Nominal Idle Delta-P: 3 - 8 mbar (< 0.12 psi)
OEM REPLACEMENTS

Zugehörige Kraftstoffsystem-Komponenten

Die folgenden Original-Kraftstoffpumpen und Common-Rail-Injektoren sind verifizierte Werksausrüstungen für Motoren mit dem Fehlercode P2453. Prüfen Sie Betriebsdrücke und Anzugsdrehmomente vor dem Austausch:

Common Rail Injector

0445110369BOSCH

0445110369 Injector: VW 2.0 TDI EA189 CFFB CFHC Specs

View Technical Specs & Fitment →
Common Rail Injector

0445116024BOSCH

BOSCH 0445116024 Common Rail Piezo Injector for BMW N47 2.0d & N57 3.0d

View Technical Specs & Fitment →
CALIBRATION RELEARN

Hochdruckpumpen-Adaptionsreset & Anlernfahrt

Following the replacement of the DPF differential pressure sensor, hose repair, or DPF replacement for DTC P2453:

1. Clear all active and pending diagnostic trouble codes from the Engine Control Module.

2. Access ECM Special Functions -> 'DPF Differential Pressure Sensor Adaptation / Zero Point Calibration'.

3. Switch ignition ON with engine OFF for at least 30 seconds without starting the engine to allow the ECM to record the 0 mbar voltage baseline.

4. Start the engine and idle until coolant temperature exceeds 80°C.

5. Conduct an adaptation test drive: drive for 20 minutes at speeds between 60 km/h and 100 km/h with steady-state cruising to verify that the ECM enables automatic DPF soot load tracking and clears readiness monitors.

DIFFERENTIAL DIAGNOSIS

Differenzialdiagnose & Verwandte Fehler

P2452

Diesel Particulate Filter Pressure Sensor 'A' Circuit

P2454

Diesel Particulate Filter Pressure Sensor 'A' Circuit Low

P2455

Diesel Particulate Filter Pressure Sensor 'A' Circuit High

P2463

Diesel Particulate Filter - Soot Accumulation

FIELD REPAIR REPORTS

Praxisfälle aus der Werkstatt

CASE #1

2015 Ford Focus 1.6 TDCi (DV6C Euro 5)(168,000 km)

Reported Complaint:Check engine light on with P2453; vehicle unable to complete active DPF regeneration cycles.
Teardown Root Cause:Previous workshop installed new differential pressure sensor, but fault reoccurred instantly. Live data showed 28 mbar differential pressure with Key-On Engine-OFF (should be 0 mbar). Disconnecting rubber hoses revealed the upstream metal sampling tube was completely plugged with hardened carbon slag, trapping exhaust pressure inside the rubber hose.
Repair Solution:Cleared steel sampling line with 1.5mm wire and carburetor cleaner, blowing out carbon debris with shop air. Reconnected sensor: KOEO read exactly 0 mbar, and idle pressure settled at 5 mbar. Successful dynamic DPF regeneration completed.
DIAGNOSTIC FAQ

Häufig gestellte technische Fragen

Was bedeutet der Fehlercode P2453?

Der Diagnose-Fehlercode (DTC) P2453 weist darauf hin, dass das Motorsteuergerät (EDC/MSG) einen Plausibilitäts-, Messbereichs- oder dynamischen Korrelationsfehler im Signal des Dieselpartikelfilter-Differenzdrucksensors 'A' festgestellt hat. Im Gegensatz zu einem Kurzschluss oder einer Leitungsunterbrechung wird P2453 gesetzt, wenn der Sensor eine elektrisch valide Signalspannung liefert, der resultierende Differenzdruckwert jedoch im Widerspruch zur realen Abgasströmungsdynamik steht. Typische Auslösebedingungen sind: (1) Nullpunkt-Offset-Drift bei Zündung EIN und Motor AUS (Sensor meldet Druck ohne Abgasmassenstrom); (2) Sensorwert bleibt statisch oder reagiert träge bei dynamischen Lastwechseln unter Volllast; (3) Negativer Differenzdruck infolge vertauschter Druckentnahmeleitungen; oder (4) Gerissene bzw. undichte Druckschläuche mit Abblasen gegen Umgebungsdruck.

Was sind die häufigsten Symptome von P2453?

Check Engine Light (MIL) illuminated continuously on the dashboard, Flashing DPF warning icon or 'Exhaust Filter Fault' message in the driver information center, Engine enters Limp-Home mode with sluggish throttle response and power capped below 3,000 RPM, Automatic DPF soot regenerations blocked, leading to rapid soot accumulation and exhaust backpressure, Higher fuel consumption and exhaust tailpipe soot smell, Scan tool live data displays zero differential pressure or negative values during hard acceleration.

Was verursacht P2453 bei einem Dieselmotor?

Cracked, burned through, melted, or detached rubber pressure sampling hoses between DPF and sensor; Pressure sampling hoses inadvertently reversed during previous DPF or transmission servicing; Zero-drift calibration shift in the sensor's piezoresistive silicon diaphragm due to thermal shock or aging; Hard carbon soot or crystallized exhaust moisture plugging the metal pressure sampling pipes on the DPF canister; Intermittent high contact resistance or terminal fretting in the 3-pin sensor electrical connector; Internal soot cake crack or hollowed-out DPF ceramic core causing actual pressure drop to be near zero.

Kann man mit Code P2453 noch weiterfahren?

🟡 Achtung: Notlauf aktiv / Zeitnah Werkstatt aufsuchen

Was kostet die Reparatur von Fehlercode P2453?

Die typischen Reparaturkosten für Fehlercode P2453 hängen von der Schadensursache und Diagnosestufe ab: Stufe 1 (Kleinreparatur / Wartung): 35 € - 80 €: Ruß aus Druckleitungen entfernen und Nullpunktabgleich per Diagnosetester durchführen (Sensorreinigung, Kraftstofffilterwechsel, Sicherungsprüfung oder Steckerkontaktreinigung.); Stufe 2 (Komponententausch): 90 € - 240 €: Einbau eines neuen Original-DPF-Differenzdrucksensors (Austausch von Einzelkomponenten (z. B. Druckbegrenzungsventil, Zumesseinheit oder instandgesetzter Injektor).); Stufe 3 (Baugruppenüberholung): 750 € - 2.200 €: Professionelle DPF-Reinigung im ausgebauten Zustand oder Filterelement-Austausch (Überholung der Hochdruckpumpe, neuer OEM-Injektorsatz oder Austausch der DPF-Baugruppe.). Werkstatt-Richtwerte. Daten belegen, dass über 70% der Fälle in Stufe 1 oder 2 ohne Tausch kompletter Baugruppen behoben werden.

Can a split DPF pressure hose cause P2453?

Yes! In fact, a split or melted upstream rubber hose is the number one cause of P2453 in common rail workshops. When the hose ruptures, exhaust gas leaks out into the engine bay, and the sensor measures near-zero pressure even at wide-open throttle, causing the ECM to flag a plausibility failure.

What happens if the two pressure hoses are connected backward?

If the hoses are swapped, the sensor reads higher pressure on the downstream port than the upstream port, producing a negative pressure reading (e.g. -20 mbar / 0.35V). The ECM recognizes negative exhaust pressure as physically impossible and immediately triggers DTC P2453.

Why does P2453 trigger right after starting the car?

The ECM performs a mandatory zero-point plausibility check before the engine even cranks (Key-ON Engine-OFF). If the sensor reports a residual pressure above 10 mbar due to internal diaphragm fatigue, the ECM flags P2453 instantly before the starter engages.