What it means
The MAP B signal drops out or jumps intermittently. Loose connector or noisy ground reference. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
MAP B measures intake manifold pressure and sends the ECM a signal used to estimate engine load. This code sets when that signal drops out or jumps unpredictably, often because vibration interrupts a connector contact or the sensor ground reference is unstable.
Common causes
Most likely first.
- Sensor connector not seated
- Noisy ground reference
- Connector with intermittent contact under vibration
Symptoms
- Check-engine light
- Rough idle
- Hesitation or surging
How to diagnose it
- Save freeze-frame data and graph MAP B with the primary MAP reading and RPM to see whether the fault coincides with vibration or changing engine load.
- Inspect the MAP B connector for incomplete seating, moisture, corrosion, loose pins, and signs of pin push-back.
- Check the sensor ground and wiring for chafing, loose splices, or other damage that could create an unstable reference.
- With live data displayed, gently wiggle the MAP B connector and harness to see whether the reading jumps or drops out.
- If the harness and ground remain stable, test MAP B output under changing pressure against the manufacturer's specification.
Common fixes
- Seat and secure the MAP B connector.
- Clean or repair terminals with intermittent contact.
- Repair damaged or chafed wiring and restore a stable sensor ground.
- Replace MAP B if its signal remains erratic with sound wiring and connections.
Can I keep driving?
Drive only if the engine response remains predictable, and avoid heavy traffic or hard acceleration if it hesitates or surges. Stop if the signal fault causes stalling or sudden loss of power.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.