P2495

Reductant Heater Control Circuit High Bank 1

P2495 is a generic OBD-II powertrain diagnostic trouble code: Reductant Heater Control Circuit High Bank 1. 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
P2495
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on)
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What P2495 means

P2495 is logged when the aftertreatment control module detects an unexpectedly high voltage or current condition in the control circuit for the diesel exhaust fluid (DEF) heater on Bank 1. Some larger diesel applications use multiple heating zones or banks within the DEF delivery system to ensure proper thawing of urea solution throughout the supply lines and injector in cold ambient temperatures. Bank 1 refers to the primary heating zone.

A high-circuit fault typically indicates a short to voltage in the control wiring, an open in the low-side driver path, or a failed heater relay that is not releasing and is supplying unswitched power back to the circuit monitor. The control module compares the expected circuit state against the measured voltage; when the circuit reads high while the heater is commanded off, or current exceeds the upper limit when commanded on, P2495 is set.

Because DEF is corrosive and operates in a harsh under-vehicle environment, connector corrosion and harness chafing are frequent causes. Diagnosis should begin with a thorough visual inspection of the heater circuit before electrical measurements are taken. Persistent faults in the heater system can lead to SCR system inoperability in cold weather and trigger power derating on vehicles with strict emissions compliance requirements.

Common causes

Most-frequently reported root causes when P2495 is logged.

  • 1
    Short to voltage in the DEF heater Bank 1 control wiring or connector.
  • 2
    Failed heater relay with stuck contacts supplying unswitched power to the circuit.
  • 3
    Open low-side driver circuit in the control module causing a floating high signal.
  • 4
    Corroded or bridged connector pins at the heater element due to DEF crystallization.
  • 5
    Chafed wiring harness shorting to battery-positive routing near the fuel or DEF tank.
  • 6
    Internal heater element failure causing resistance outside the expected range.

Symptoms drivers notice

MIL or SCR system warning lamp illuminated.
DEF heater inoperative warning in cold conditions.
Possible loss of DEF flow in sub-freezing temperatures leading to SCR system shutdown.
Inducement strategy (engine power limitation) may activate if DEF system remains non-functional.

How to diagnose P2495

A typical diagnostic flow when this code is present.

  1. 1
    Retrieve all stored DTCs; note companion codes for DEF level, quality, temperature, or NOx efficiency.
  2. 2
    Inspect the Bank 1 heater wiring harness and connector for chafing, corrosion, or DEF deposits.
  3. 3
    Measure voltage on the heater control line with the heater commanded off; voltage should be near zero.
  4. 4
    Check the heater relay for stuck contacts by measuring output voltage with the relay de-energized.
  5. 5
    Measure heater element resistance and compare to specification; replace the element if out of range.
  6. 6
    If wiring, relay, and element pass inspection, test the control module driver output before assuming module failure.

Vehicles where we've handled P2495

Platforms in our catalogue with confirmed P2495 coverage.

BMW 320D
2016

Related powertrain codes

Frequently asked questions

What does 'Bank 1' mean in P2495?

Bank 1 identifies the primary DEF heating zone in systems with multiple heater circuits; it does not refer to engine cylinder banks in the traditional combustion sense.

Can P2495 cause an engine derate in summer?

In warm weather the heater is rarely commanded on, so a circuit fault may not immediately affect DEF delivery; however the stored fault can still trigger an emissions-compliance warning leading to eventual inducement.

Is P2495 different from P241D?

Yes. P241D is a general reductant tank heater circuit fault, while P2495 specifically identifies a high-circuit condition on Bank 1 of a multi-zone heater system.

Can DEF crystals cause a circuit fault?

Yes. Crystallized DEF deposits can bridge connector pins, creating unintended electrical paths that the module interprets as a circuit anomaly.

Disabling P2495 in software

RaceTune can permanently disable P2495 — 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.

ECUs with a P2495 disable in our catalogue

Confirmed coverage from our recipe database — we support many more families. Upload your file and our identifier will match it automatically.

  • Bosch EDC17C50 verified 1 software version
  • Bosch EDC17CP09 verified 1 software version

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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