P2A0A: Manifold Absolute Pressure Sensor B Circuit

What it means

The ECM detects a generic fault on the secondary manifold absolute pressure sensor (MAP B). Air load estimation cannot be cross-checked.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test

How it works

MAP B measures absolute pressure in the intake manifold, giving the ECM a second pressure signal to compare with engine load and the primary MAP reading. This code sets when the ECM detects a general electrical fault in the MAP B circuit, without identifying a specific low, high, or erratic signal condition.

Common causes

Most likely first.

1. MAP B sensor failed
2. Wiring or connector fault

Symptoms

• Check-engine light
• Rough idle
• Poor acceleration

How to diagnose it

1. Use a scan tool to record freeze-frame data and compare MAP B with the primary MAP reading, throttle position, and engine speed to see when the fault occurred.
2. With the engine off, inspect the MAP B connector, sensor body, and nearby harness for loose pins, corrosion, damage, or contamination.
3. Check the MAP B wiring for continuity and shorts, and inspect its power and ground connections using the vehicle wiring diagram.
4. Compare MAP B output with intake conditions and the manufacturer's specification, then test the sensor and circuit separately to locate the fault.

Common fixes

• Reconnect and secure the MAP B connector or repair damaged wiring.
• Clean or repair corroded connector terminals and restore sound power and ground connections.
• Replace the MAP B sensor if its output is faulty after wiring checks.

Can I keep driving?

If the engine runs smoothly, a short, gentle drive may be possible, but avoid hard acceleration and long trips. Rough running or poor acceleration can make merging and passing unsafe, so stop driving if the engine begins stalling.