P220F

Code

Generic P — Powertrain

NOx Sensor Heater Control Circuit Range/Performance Bank 1 Sensor 2

Brand: Generic

Type: P — Powertrain

Views: UK: 40 EN: 102 RU: 43

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Page language: EN

Causes

Open or shorted heater circuit (wiring or connector)
Corroded or damaged sensor connector or pins
Blown fuse or failed heater relay
High resistance in circuit (corroded ground, poor splice)
Failed NOx sensor heater element
PCM (control module) driver fault

Symptoms

MIL (Check Engine Light) illuminated
Failed emissions test or elevated NOx emissions
Extended sensor warm-up time leading to incorrect NOx readings
Regeneration/aftertreatment control may be affected or inhibited
Possible limp mode or reduced emissions control in some vehicles
Possible stored or pending related NOx or aftertreatment codes

What to check

Retrieve freeze frame and all related/secondary codes with a scan tool
Visually inspect Bank 1 Sensor 2 connector, wiring harness, and sensor for damage or corrosion
Verify fuses and relays for the heater circuit are intact and functioning
Backprobe heater power and ground pins while commanding heater ON and OFF with a capable scan tool
Measure heater element resistance at the sensor (with harness disconnected)
Perform voltage drop tests and continuity checks on heater power and ground circuits

Signal parameters

Heater supply voltage (when commanded ON): near battery voltage (~11–14.5 V)
Heater circuit resistance (typical): manufacturer-specific; commonly in the low ohm range (approx. 2–50 Ω) — compare to service spec
Heater current draw when ON: typically hundreds of mA to a few amps (0.3–3 A) depending on sensor design
PCM command/duty cycle: 0–100% (check for expected PWM when controlled)
Open-circuit: infinite resistance (no continuity) indicates open heater
Short to ground: near 0 Ω between heater power and ground

Diagnostic algorithm

Read and record active and pending codes and freeze frame data. Note when the code sets (cold start, after regen, etc.).
Perform a visual inspection of Bank 1 Sensor 2, its connector, and wiring for damage, corrosion, or contamination. Repair obvious damage.
Check fuses and relays supplying the NOx heater circuit. Replace any blown fuses and test relays. Re-scan for codes.
Unplug the sensor connector. With an ohmmeter, measure heater element resistance at the sensor pins. Compare to service spec. Infinite = open; very low = short.
With the harness connected, backprobe the heater power feed and ground. Using a scan tool, command the heater ON and monitor voltage at the power pin. Voltage should approach battery voltage when commanded ON.
If commanded voltage is present but resistance/current is abnormal, suspect the sensor heater element or internal short — consider replacing sensor.
If no commanded voltage at sensor while PCM requests heater ON, check continuity between sensor connector and fuse/relay/battery, including ground path. Repair open or shorted wiring, splices, or corroded connectors.
If wiring and sensor check good, test PCM heater driver output for shorts to ground or power. Use manufacturer procedures; avoid direct bench testing without proper tools. Replace PCM only after eliminating wiring and sensor faults.
After repairs or sensor replacement, clear codes and perform a drive cycle or required readiness tests to confirm the fault does not return.
If intermittent, perform wiggle/road test and monitor live data to confirm stability under operating conditions.

Likely causes

Broken or chafed harness between PCM and Bank 1 Sensor 2
Corroded connector causing intermittent contact or increased resistance
Open fuse or failed relay supplying heater power
Failed heater element inside the NOx sensor
Short to battery or ground at the heater power lead
Bad ground at sensor mounting or chassis ground

Fault status

⚠️ Status

NOx sensor heater control circuit for Bank 1 Sensor 2 is out of expected range or not performing correctly. The PCM detected abnormal heater operation (open, short, high resistance, low current, or driver failure).

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours