P2EAD

Code

Generic P — Powertrain

Reductant Metering Unit 2 Performance

Brand: Generic

Type: P — Powertrain

Views: UK: 18 EN: 34 RU: 20

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Page language: EN

Causes

Metering unit 2 (valve/actuator) mechanical failure
Clogged reductant supply, filter or nozzle (crystallization)
DEF contamination, depleted or frozen DEF
DEF pump or supply pressure fault upstream of metering unit
Wiring harness damage, poor connector connection, or pin corrosion
Faulty driver circuit in ECM/TCM controlling the metering unit

Symptoms

Malfunction Indicator Lamp (MIL) or check-engine light illuminated
Reduced/no reductant dosing for that bank; elevated NOx or aftertreatment fault codes
Possible reduced engine power or derate if vehicle enters limp/emission-protection mode
Increased DEF consumption or warnings about SERVICE SCR system
Stored freeze-frame data showing dosing command vs actual mismatch

What to check

Read/freeze-frame data for P2EAD and any related aftertreatment/DEF codes
Check DEF level, quality and temperature (frozen or contaminated DEF)
Visually inspect metering unit 2, lines, filter and nozzle for crystals, deposits or leaks
Inspect connector and wiring for corrosion, damaged insulation, or loose pins
Measure supply voltage at the metering unit connector (battery voltage expected when key on)
Command metering unit on/off using a scan tool and observe response (actuation, current draw, duty cycle)

Signal parameters

Supply voltage: ~11–14.5 V with key on/run (vehicle battery range)
Control signal: PWM duty cycle 0–100% commanded by ECM (varies with dosing need)
Typical actuator resistance: manufacturer-specific — expect low ohms to a few tens of ohms; compare to service spec
Current draw while actuated: typically
Response time: actuator should respond within a few hundred milliseconds of command (verify with OEM spec)
Measured flow/pressure: expected positive correlation with commanded duty cycle — no/very low flow at 0% and increasing flow as duty increases (quantitative values are model-specific)

Diagnostic algorithm

Safety first: park on level ground, key off, allow exhaust/DEF components to cool; follow facility PPE and DEF handling guidance.
Scan for codes: record P2EAD and any related P2E/ P20* codes; save freeze-frame and live data.
Check DEF: verify level, check for crystallization or discoloration; if frozen, allow to thaw and retest.
Visual inspection: inspect metering unit 2, plumbing, filters and nozzle for deposits, leaks or damage; clean mild crystals per OEM guidance.
Electrical check: disconnect connector, inspect pins; with key on measure supply voltage and ground at connector; then measure coil/actuator resistance to service spec.
Command test: using a capable scan tool command the metering unit (vary PWM/duty) and observe current, audible actuation and change in dosing/pressure/live data.
Flow/pressure: measure reductant pressure/flow upstream and downstream of metering unit while commanding dosing. Low or no flow with correct command indicates mechanical restriction or pump issue.
Wiring/continuity: check harness for opens/shorts/short-to-ground and high resistance; wiggle test while monitoring live data.
Swap/compare: if possible, swap meter unit with known-good unit or compare operation to bank 1 to isolate ECU vs unit failure.
Module verification: if wiring and unit test good, confirm ECM/aftertreatment controller outputs and software level; reflash/update if OEM procedure suggests.
Repair and verify: repair or replace defective component (filter, lines, metering unit, pump, wiring or module), clear codes, perform relearn if required, and run drive cycle/verification to confirm code does not return.