B1492 — Ignition Cylinder Sensor Open Circuit

OBD2 code B1492 flags a problem with the ignition system (ignition cylinder sensor open circuit). Short, gentle driving to a shop is usually possible. Common culprits: moisture or oil in the spark plug wells, faulty ignition control circuit in the ECM, failed ignition coil or coil pack.

body electrical

Is it safe to drive?

Drive with caution Drive with caution and avoid load. Ignition faults cause misfires that quickly overheat and destroy the catalytic converter; if the Check Engine Light flashes, stop and fix it first.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm B1492 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many B0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the ignition system for damage, corrosion, chafing or poor contact.
Subsystem check Swap the coil to another cylinder and see if the fault code follows it.
Subsystem check Inspect spark plugs for wear, oil or carbon tracks and check plug gaps.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm B1492 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for B1492 (parts and labor, USD, independent shop rates): Repair coil wiring or connector: $80–$250; Replace spark plugs: $90–$250; Replace an ignition coil: $150–$380. Overall, fixing B1492 usually costs between $80 and $380. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

Is it safe to drive with B1492?

Drive with caution and avoid load. Ignition faults cause misfires that quickly overheat and destroy the catalytic converter; if the Check Engine Light flashes, stop and fix it first.

What does OBD2 code B1492 mean?

What are the symptoms of B1492?

Drivers most often notice: increased fuel consumption, Check Engine Light on, loss of power and jerking, hard starting, especially in damp weather.

How do I diagnose B1492 myself?

Start with a scan: confirm B1492, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the ignition system, and verify the suspect component against live data before buying parts.

What is the most common cause of B1492?

The most common causes are: moisture or oil in the spark plug wells, faulty ignition control circuit in the ECM, failed ignition coil or coil pack.

When your OBD2 scanner displays code B1492, it means the vehicle's control module has identified a problem with the ignition system operating outside its factory-calibrated parameters. Specifically, B1492 translates to "Ignition Cylinder Sensor Open Circuit," a fault that falls within the body electrical category but directly affects how the engine runs. The PCM constantly monitors the voltage and resistance flowing through the ignition sensor circuit. When those readings drop below acceptable thresholds or the circuit goes completely silent, the module logs B1492 and turns on the Check Engine Light.

To trigger B1492, the control unit typically needs to observe the anomaly across multiple drive cycles—not just a single brief interruption. When the code sets, the PCM also records a freeze frame snapshot containing engine speed, load percentage, coolant temperature, and vehicle speed at the exact moment of failure. That snapshot is gold during diagnosis because it tells you exactly what conditions were present when the fault occurred, helping you reproduce the problem rather than chasing ghosts.

The ignition cylinder sensor feeds critical data back to the engine computer, allowing precise control of spark timing and fuel delivery. Without reliable sensor feedback, the PCM essentially flies blind. It cannot adjust timing for load changes, temperature shifts, or acceleration demands, which explains why ignition-related codes cause such noticeable drivability problems.

Symptoms of B1492

The Check Engine Light illuminates and may flash under certain conditions
Noticeable increase in fuel consumption compared to normal driving
Engine hesitates, stutters, or delivers sluggish acceleration
Hard starting, particularly in humid or wet weather when moisture can interfere with ignition
Misfires that may occur at idle or under engine load
In some cases, a partial or complete loss of engine power

Common Causes

Damaged wiring or corroded connectors in the ignition coil circuit
Faulty ignition coil or failing coil pack unable to deliver consistent spark
Worn or improperly gapped spark plugs
Moisture intrusion or oil contamination in the spark plug tube wells
Sensor internal failure or connector damage at the cylinder sensor itself

How to Diagnose B1492

Connect an OBD2 scanner, verify B1492 is stored, and capture the freeze frame data before clearing anything—this recording shows engine conditions when the fault first appeared.
Look for additional trouble codes that may point to the root cause. Check manufacturer technical service bulletins for your specific make and model, as many B-series codes have documented factory fixes or software updates.
Perform a thorough visual inspection of the ignition system wiring harness and connectors, paying close attention to damaged insulation, corrosion, bent pins, or loose connections.
Test the suspected coil by swapping it with a known-good cylinder coil, then monitor whether the fault code migrates to the new location.
Remove and inspect spark plugs for excessive wear, oil fouling, carbon buildup, or incorrect electrode gap.
Clear the code, complete a test drive that reproduces the freeze frame conditions (same speed, load, and temperature), and verify B1492 does not return.

Repair Options and Costs

Addressing B1492 means targeting whichever ignition component triggered the open circuit. Repair options include:

Wiring or connector repair: $80–$250
Spark plug replacement: $90–$250
Ignition coil replacement: $150–$380

Prices reflect typical parts and labor at an independent repair shop in USD.

The total cost to resolve B1492 typically falls between $80 and $380, depending on which component failed. Always diagnose before purchasing parts—an accurate assessment prevents wasted money on the most expensive fix when the problem may be as simple as a loose connector or worn plug.

Driving Safety Verdict

B1492 warrants a caution classification. While the vehicle may still move, unresolved ignition faults cause misfires that introduce unburned fuel into the exhaust stream, quickly overheating and destroying the catalytic converter. If the Check Engine Light begins flashing, stop driving immediately and address the issue—flashing indicates an active misfire that demands urgent repair.