P243A

Code

Generic P — Powertrain

Particulate Filter Restriction - Ash Accumulation Bank 2

Brand: Generic

Type: P — Powertrain

Views: UK: 25 EN: 44 RU: 26

AI status

Completed

ready

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Page language: EN

Causes

DPF has reached end-of-life for ash loading (normal wear)
Excessive engine oil consumption or oil burning (worn piston rings, turbo oil seal, leaking injectors)
Excessive EGR flow or faulty EGR cooler increasing particulate production
Use of inappropriate oil or fuel additives that leave ash
Incomplete or infrequent regeneration history (short trips) accelerating ash accumulation
Damage or improper servicing of DPF/DPF cleaning, or use of incorrect replacement part

Symptoms

MIL/engine warning lamp on with P243A stored
Reduced engine power or derate/limp mode
Increased fuel consumption
Frequent active regenerations attempted or forced regen unavailable
Noticeable exhaust restriction / reduced turbo boost
Unusual smoke color (may be darker) during acceleration

What to check

Read and record all stored/pending codes and freeze frame data
Verify vehicle history: DPF age, mileage, past regeneration events and service records
Check for related codes (EGR, injectors, turbo, pressure/temperature sensors)
Visual inspection of exhaust system for leaks, damage to DPF or mounting
Inspect differential pressure sensor, tubing and connector for blockages, contamination or damage
Compare upstream and downstream exhaust temperature sensors while driving or during a regen cycle

Signal parameters

DPF differential pressure (ΔP) — idle and loaded values; rising baseline indicates restriction
Upstream exhaust temperature (°C/°F) — high during regen; compare to downstream temp
Downstream exhaust temperature
DPF soot mass or ash mass (if available from OEM tool)
Engine load/percent torque and RPM during recorded event
Fuel rail pressure and injector balance (if suspect soot source)

Diagnostic algorithm

Verify code P243A is current; record freeze frame and related codes. Clear codes and re-run to confirm repeatability.
Inspect wiring/connections and tubing for the DPF differential pressure sensor; repair or replace if corroded, blocked, or damaged.
Using a scan tool, monitor ΔP, upstream/downstream temperatures and soot/ash counters. Compare values to manufacturer thresholds and note trends under idle and load.
Check for sources of excess oil or soot: measure oil consumption, inspect turbocharger seals, inspect injectors for leaks/poor spray pattern, and test EGR operation.
Inspect exhaust for leaks between the engine and sensors which can give false readings.
Attempt a controlled/forced regeneration if ash is not confirmed (only if soot load indicates regeneration may help). If ΔP remains high after successful regen or regen cannot clear the condition, suspect ash buildup.
If ash accumulation is confirmed (high ash mass value or persistent high ΔP after regen), plan for DPF servicing: professional decanning/cleaning per OEM procedures or replacement of the DPF assembly.
Replace or clean differential pressure sensor, temperature sensors, and any damaged hardware during DPF service. Repair root causes (EGR, injectors, turbo, oil consumption) to prevent recurrence.
Update ECM software if a TSB/factory calibration is available for adaptive DPF strategies. Clear codes and road-test to verify repair.
If condition persists after hardware/service and controls check, escalate to OEM diagnostic procedures or factory support.

Likely causes

DPF physically clogged with ash (non-combustible) beyond regen capability
High oil consumption feeding ash-forming contaminants into filter
Faulty differential pressure sensor or clogged/blocked sensor tubing
Excessive soot production from failing injectors or turbocharger issues
EGR system malfunction increasing particulate formation
Previous incorrect DPF cleaning or use of improper regeneration procedure

Fault status

⚠️ Status

Particulate Filter Restriction — Ash Accumulation Bank 2. DPF ash loading exceeded allowable threshold; check DPF condition, differential pressure sensor, and upstream causes (oil consumption, EGR, injectors).

🔴 Repair difficulty: Hard

⏱️ Diagnostic time: 2-6 hours