P220A code meaning
NOx Sensor Supply Voltage Circuit (Bank 1 Sensor 1)
Powertrain system Generic code P22xx codes Check engine light
What P220A means
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.
P220A at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P220A
- Malfunction indicator lamp on
- Upstream NOx sensor shows no value or no communication
- Other NOx sensor codes stored at the same time
Common causes of P220A
- Most likelyBlown fuse, faulty relay or poor ground in the sensor supply
- PossibleSupply wire chafed, corroded or with high resistance
- PossibleSupply booster in the glow plug control module (GM 6.6L LML)
- Less likelyWeak battery or charging-system voltage out of range
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Nox sensorNox sensor supply relay
What each part of P220A means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 2 | Area: fuel and air metering (injector circuit). |
| 0A | The exact fault in that area. |
What to do next
- Note P220A and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P220A
What does P220A mean?
P220A means "NOx Sensor Supply Voltage Circuit (Bank 1 Sensor 1)". A smart NOx sensor draws its own operating power, mostly for the probe heater. It is a generic code, so it means the same on every make.
Is it safe to drive with P220A?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P220A fail an emissions test?
Yes, it can. P220A is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P220A to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P220A clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.