P2D36

Reductant Injection Valve A Control Circuit Open

P2D36 is a generic OBD-II powertrain diagnostic trouble code: Reductant Injection Valve A Control Circuit Open. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P2D36
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on, possible limp mode)
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What P2D36 means

P2D36 is set when the ECM or SCR dosing control module detects an open circuit in the control circuit for reductant injection valve A. The reductant injector, also called the DEF or AdBlue dosing injector, sprays precisely metered quantities of DEF into the exhaust stream upstream of the SCR catalyst. Accurate dosing is required to reduce NOx emissions to regulated levels.

An open control circuit means the module cannot drive current through the injector solenoid, preventing all DEF dosing from that injector. The SCR system will be unable to reduce NOx, causing emissions non-compliance. Many calibrations trigger a regulatory derate sequence when dosing is confirmed inoperative across multiple drive cycles to compel the driver to have the fault repaired.

Possible causes include a broken wire in the injector control harness, a failed injector solenoid coil, a blown fuse in the dosing system power supply, or a faulty ECM or dosing module driver output. Measure solenoid coil resistance and verify supply voltage before condemning the injector or module.

Common causes

Most-frequently reported root causes when P2D36 is logged.

  • 1
    Open circuit in the reductant injector control wire.
  • 2
    Failed DEF injector with an open solenoid coil.
  • 3
    Blown fuse or failed relay in the reductant dosing supply circuit.
  • 4
    Broken connector pin or terminal at the injector.
  • 5
    Damaged wiring harness in the exhaust area exposed to heat.
  • 6
    Faulty dosing control module or ECM output driver.
  • 7
    Open injector ground return circuit.

Symptoms drivers notice

MIL and SCR/NOx warning lamps illuminated.
No DEF dosing occurring, resulting in high NOx output.
Possible progressive torque derate after fault persists across drive cycles.
SCR catalyst efficiency sharply reduced.
Scan tool may show zero DEF injector duty cycle or no injection activity.

How to diagnose P2D36

A typical diagnostic flow when this code is present.

  1. 1
    Connect scan tool and read all DTCs in the SCR and engine control modules.
  2. 2
    Check live data for DEF injector A commanded duty cycle versus actual activation.
  3. 3
    Locate the DEF injector and inspect its connector and wiring for damage or heat exposure.
  4. 4
    Measure DEF injector solenoid coil resistance; open reading confirms coil failure.
  5. 5
    Check supply voltage and fuse for the dosing system with ignition on.
  6. 6
    Test injector control wire continuity and check for open circuit between module and injector.
  7. 7
    Command the injector on with a scan tool; if supply and wiring are good, replace injector if no activation occurs.

Related powertrain codes

Frequently asked questions

Can a clogged DEF injector cause P2D36?

No. A mechanical blockage does not create an open electrical circuit; P2D36 is specifically an electrical open circuit fault in the control wiring or solenoid.

How long before a derate is imposed?

This varies by manufacturer and regional emissions regulation, but many systems allow a limited number of engine starts or a mileage threshold before enforcing derate.

Is P2D36 specific to one injector?

Yes, the A designation refers to injector A, which is the primary dosing injector; some heavy-duty applications may have multiple injectors with separate codes.

What is normal DEF injector solenoid resistance?

Resistance specifications vary by manufacturer; always refer to the vehicle-specific service data rather than assuming a generic value, as using incorrect values can lead to misdiagnosis.

Disabling P2D36 in software

RaceTune can permanently disable P2D36 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

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