Powertrain, generic (extended)

P220A NOx Sensor Supply Voltage Circuit (Bank 1 Sensor 1)

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

A smart NOx sensor draws its own operating power, mostly for the probe heater. P220A means the supply reaching the upstream sensor on bank 1 is outside its window. Ford's 6.7L and 3.0L diesels flag above 16.5 V or below 8.5 V; GM's 3.0L Duramax (LZ0) flags below 9.9 V while the engine runs, Type B after two trips. On the 6.6L LML, GM feeds the sensor from a DC/DC booster in the glow plug module and sets P220A when that module reports its output shorted or overloaded (Type B). VW's 2014 Touareg TDI uses a 1.5 V deviation. Volvo and Mack advise checking supply wiring, fuses and relays rather than the sensor. P220B is the downstream sensor, P220C/P220D bank 2. The sensor stays inactive.

Likely causes

Blown fuse, faulty relay or poor ground in the sensor supply
Supply wire chafed, corroded or with high resistance
Supply booster in the glow plug control module (GM 6.6L LML)
Weak battery or charging-system voltage out of range

Symptoms

  • Malfunction indicator lamp on
  • Upstream NOx sensor shows no value or no communication
  • Other NOx sensor codes stored at the same time

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€30–800
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

nox sensornox sensor supply relay

Related codes

P220BP220CP220DP2200U029D

References: fordservicecontent.com, gsi.ext.gm.com, gsi.ext.gm.com, static.nhtsa.gov.