P1198

Code

VOLKSWAGEN P — Powertrain

Oxygen Sensor Heater Circuit Bank 1 Sensor 2 Electrical Malfunction

Brand: VOLKSWAGEN

Type: P — Powertrain

Views: UK: 33 EN: 48 RU: 36

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Page language: EN

Causes

Failed oxygen sensor heater element (internal open or short)
Open or shorted wiring in heater circuit (connector to sensor or to PCM)
Corroded, loose or damaged sensor connector pins
Blown fuse or faulty relay supplying the heater circuit
Defective power or ground circuit (high resistance)
Faulty engine control module (rare)

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
Failed emissions test or elevated tailpipe emissions
Reduced catalyst monitoring readiness (incomplete readiness)
No noticeable engine driveability problems in many cases
Possible stored or pending related codes (other O2 sensor codes)

What to check

Read freeze frame and live data for O2 heater status using a scan tool
Check for additional related codes (other O2 sensor heater or sensor codes)
Inspect sensor connector for corrosion, bent pins, or water damage
Verify relevant fuses and relays for the heater circuit
Backprobe heater power and ground circuits with a multimeter/scan tool
Measure heater resistance at the sensor (with connector unplugged)

Signal parameters

Supply voltage to heater: ~11–14 V when powered (key ON/engine running depending on control strategy)
Heater circuit resistance (typical range): approximately 2–20 ohms (spec varies by sensor—consult OEM spec)
Expected current draw when heater on: approximately 0.5–3 A (depends on sensor resistance)
Heater control: may be switched latterly by PCM (on/off) or pulse-width modulated — monitor heater status parameter via scan tool

Diagnostic algorithm

Retrieve all stored/pending codes and freeze frame data with a diagnostic scanner. Note engine conditions when code set.
Visually inspect Bank 1 Sensor 2 (post-cat) harness and connector for damage, corrosion, loose wires, or water entry. Repair as needed.
Check fuses/relays supplying O2 heater circuits; replace blown fuses and re-test.
With ignition off, unplug the sensor connector and measure heater element resistance across the heater terminals. Compare to OEM spec; an open or infinite reading indicates failed heater.
With ignition ON (engine off unless specified by OEM), backprobe the connector and verify battery voltage is present at the heater power terminal when the PCM commands heater on (use scan tool to command heater where possible).
Check for good ground/PCM driver: measure continuity from sensor ground pin to chassis ground and check for voltage drop during heater operation. Look for high resistance or intermittent ground.
Perform wiring continuity and short checks between the sensor connector and PCM pins (check for short-to-ground or short-to-B+).
If wiring and supply/ground are good but heater element resistance is out of spec, replace the oxygen sensor (Bank 1 Sensor 2).
If new sensor still sets the code and wiring checks are good, suspect PCM driver fault and consider PCM testing or replacement after confirming with manufacturer procedures.
Clear codes and perform test drive/monitor live data to confirm repair and readiness.

Likely causes

Bank 1 Sensor 2 heater element open (most common)
Connector corrosion or water intrusion at the sensor
Broken wire or chafed harness to the sensor heater
Fuse for oxygen sensor heaters blown or weak connection at fuse/relay
PCM driver for heater damaged (less common)

Fault status

⚠️ Status

Oxygen sensor heater circuit malfunction — Bank 1 Sensor 2 (electrical fault detected).

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

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P1198 — Oxygen Sensor Heater Circuit Bank 1 Sensor 2 Electrical Malfunction