P2274

Sensor Signal Biased/Stuck Lean Bank 1 Sensor 3

P2274 is a generic OBD-II powertrain diagnostic trouble code: Sensor Signal Biased/Stuck Lean Bank 1 Sensor 3. It is logged by the engine control unit when the scr/adblue monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P2274
Group
Powertrain
System
SCR/AdBlue
Severity
Warning (MIL on)
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What P2274 means

P2274 is set when the PCM detects a lower-than-expected voltage or frequency signal from the secondary air injection (SAI) flow or pressure sensor on Bank 2 (the cylinder bank not containing cylinder 1). The SAI system pumps fresh air into the exhaust stream during cold start to accelerate catalytic converter light-off and reduce cold-start hydrocarbon and CO emissions.

A low circuit signal on the sensor can result from a short to ground in the signal wire, a failed sensor with low output, an open in the sensor supply voltage circuit, or an actual airflow condition that is genuinely lower than the minimum threshold. The ECM relies on this sensor to confirm the SAI pump is delivering adequate flow; if the signal is low the system cannot verify proper operation and the MIL is triggered.

Because the fault is in the sensor circuit rather than the pump itself, begin diagnosis by checking the sensor wiring harness for damage, verifying supply voltage and ground at the sensor connector, and comparing the sensor output to known-good values. If the circuit checks out, the sensor itself may require replacement. Poor cold-start emissions behavior or a rattling SAI check valve can also be present alongside this code.

Common causes

Most-frequently reported root causes when P2274 is logged.

  • 1
    Short to ground on the SAI sensor signal wire for Bank 2.
  • 2
    Open circuit in the sensor 5V supply or ground reference wire.
  • 3
    Failed secondary air injection flow or pressure sensor.
  • 4
    Corroded or damaged sensor connector on Bank 2.
  • 5
    SAI pump not operating or delivering insufficient flow causing a genuine low reading.
  • 6
    Blocked or collapsed SAI inlet hose on Bank 2.
  • 7
    PCM internal fault affecting the sensor input circuit.

Symptoms drivers notice

MIL illuminated, typically on first cold start after fault is confirmed.
Possible increase in cold-start hydrocarbon and CO emissions.
Secondary air injection pump may run but emissions performance is unverified.
Possible companion codes for SAI pump circuit or Bank 1 sensor.

How to diagnose P2274

A typical diagnostic flow when this code is present.

  1. 1
    Record all DTCs including any SAI pump, relay, or Bank 1 sensor codes.
  2. 2
    Inspect the Bank 2 SAI sensor wiring harness for chafing, corrosion, or connector damage.
  3. 3
    Measure sensor supply voltage (typically 5V) and ground at the sensor connector with the key on.
  4. 4
    Measure the sensor signal voltage and compare it to the expected range from service data.
  5. 5
    Command the SAI pump on with a scan tool and observe whether the sensor reading rises.
  6. 6
    If wiring checks are satisfactory, replace the Bank 2 SAI flow/pressure sensor.
  7. 7
    Clear codes and verify the repair with a cold-start drive cycle.

Related powertrain codes

Frequently asked questions

Does P2274 affect normal driving performance?

Generally no; the SAI system operates only during cold start. Normal hot-engine driving performance is typically unaffected, but cold-start emissions will be higher.

Is P2274 the same as a failed SAI pump?

No. P2274 is specific to the sensor circuit. The pump may be operating correctly but the sensor cannot confirm it. Check sensor wiring before condemning the pump.

Can P2274 cause a failed emissions test?

Yes. If the readiness monitor for the secondary air injection system is incomplete or failed, many jurisdictions will fail the emissions inspection.

What is Bank 2?

On a multi-bank (V or horizontally opposed) engine, Bank 2 is the cylinder bank that does not contain cylinder number 1. On inline engines there is only one bank so this code would not apply.

Disabling P2274 in software

RaceTune can permanently disable P2274 — 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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