P220D: NOx Sensor Supply Voltage Circuit (Bank 2 Sensor 2)

P220D covers the last position in this group: the downstream NOx sensor on bank 2, after that bank's own SCR catalyst, has a supply voltage outside its window. It only exists on engines whose two banks keep separate aftertreatment, which none of the publicly documented diesel applications do; no manufacturer lists the code with thresholds. Ford's bank 1 rear sensor code P220B uses 8.5 to 16.5 V, a useful reference. A dead rear sensor means the efficiency monitor for the bank 2 catalyst cannot finish. CARB requires NOx sensor diagnostics to catch wiring breaks and readings beyond range. P220C is the upstream sensor on the same bank, P220B the rear sensor on bank 1. Check supply fuse, ground and connector first.

Bank 2 is the side without cylinder 1, so it only exists on V or boxer engines.

Symptoms

• Malfunction indicator lamp on
• SCR efficiency monitor for bank 2 not completed

Most likely causes

• Supply fuse, relay or ground fault for the bank 2 rear sensor
• Corroded connector exposed to road spray behind the catalyst
• Internal fault in the supply stage of the sensor module

What to check, in order

Start with the simplest. You can tick off each step.

1. Read the codes and the NOx data before and after the SCR catalyst
2. Check the sensor's connector and wiring
3. Look for exhaust leaks ahead of the sensor
4. Confirm that the AdBlue/DEF is of good quality
5. Replace the sensor only after ruling out power, ground, and leaks

Good to know

• Repair difficulty: medium
• It affects emissions.

What each character of P220D means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 2: Fuel injection
• 0D: Specific fault in that system

Frequently asked questions

Can I keep driving with code P220D?

You can usually keep driving in the short term, but get it repaired soon: on many diesels, the warning eventually limits starting or engine power.

What causes code P220D?

The most common causes are: supply fuse, relay or ground fault for the bank 2 rear sensor; corroded connector exposed to road spray behind the catalyst; internal fault in the supply stage of the sensor module.

Related codes

• P220ANOx Sensor Supply Voltage Circuit (Bank 1 Sensor 1)
• P220BNOx Sensor Supply Voltage Circuit (Bank 1 Sensor 2)
• P220CNOx Sensor Supply Voltage Circuit (Bank 2 Sensor 1)
• P221BNOx Sensor 1/2 Correlation (Bank 2)

Sources

• law.cornell.edu: 13 CCR 1968.2
• fordservicecontent.com: obd summary diesel 2023
• hella.com: nitrogen oxide sensor nox sensor

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.