OBD Guide
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P11D9

O2 Pump Current Control Circuit Low Voltage (NOx Sensor 2)

P11D9 is an OBD-II diagnostic trouble code meaning: O2 Pump Current Control Circuit Low Voltage (NOx Sensor 2). Common causes: nox 2 sensor malfunction, open or short circuit in wiring harness. Estimated repair cost: $56–167.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$56–167 (est.)

Symptoms

  • Check Engine light comes on
  • Deterioration of engine performance
  • Increased fuel consumption
  • Increased level of harmful emissions
  • Possible misfires

Causes

  • NOx 2 sensor malfunction
  • Open or short circuit in wiring harness
  • Poor contact in sensor connectors
  • Engine control module malfunction
  • Sensor power problems

How to Fix

  1. Check the integrity of the NOx sensor 2 wiring harness
  2. Check sensor connectors for corrosion or damage.
  3. Check the sensor supply voltage
  4. Replace NOx 2 sensor if necessary
  5. Scan the system for other fault codes

Related codes

P11DAP11DBP11DC

FAQ

What does the P11D9 code mean?

P11D9 is an OBD-II diagnostic trouble code that indicates: O2 Pump Current Control Circuit Low Voltage (NOx Sensor 2)

What causes a P11D9 error code?

The most common causes of P11D9 include: NOx 2 sensor malfunction; Open or short circuit in wiring harness; Poor contact in sensor connectors; Engine control module malfunction.

How do I fix a P11D9 diagnostic trouble code?

To fix P11D9: Check the integrity of the NOx sensor 2 wiring harness. Check sensor connectors for corrosion or damage.. Check the sensor supply voltage. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P11D9?

Yes, but get it checked soon

How much does it cost to fix P11D9?

The estimated repair cost for P11D9 is $56–167. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat