P006B: MAP - Exhaust Pressure Correlation

What it means

The relationship between manifold absolute pressure and exhaust back pressure is implausible. One of the two pressure sensors is faulty or there is a major leak in either path.

At a glance

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

How it works

The MAP sensor measures intake manifold pressure, while an exhaust pressure sensor measures pressure in the exhaust path. The control module sets P006B when those readings have an implausible relationship, which can result from a faulty exhaust pressure sensor or a leak in the exhaust or DPF path.

Common causes

Most likely first.

1. Exhaust back-pressure sensor faulty
2. DPF or exhaust path leak

Symptoms

• Check-engine light on
• Reduced engine power
• Poor acceleration
• Exhaust warning light may come on

How to diagnose it

1. Record freeze-frame data and compare MAP and exhaust pressure live readings under the conditions that set the code.
2. Inspect the exhaust pressure sensor hoses and exhaust connections for splits, disconnections, soot traces, or other signs of leakage.
3. Check the exhaust pressure sensor connector and wiring for corrosion, damage, or loose pins.
4. Check the DPF and surrounding exhaust path for leaks or damage that could distort the pressure reading.
5. Test the exhaust pressure sensor circuit and compare readings with the manufacturer's specification before replacing parts.

Common fixes

• Reconnect or replace a split exhaust pressure sensor hose.
• Repair a leaking exhaust or DPF connection.
• Repair damaged or corroded exhaust pressure sensor wiring or connector terminals.
• Replace the exhaust pressure sensor if it fails the manufacturer's checks.

Can I keep driving?

Drive only as needed if power and engine behavior remain normal, and avoid heavy loads. Stop if power falls substantially or an exhaust warning appears, because an exhaust leak or pressure fault can worsen emissions and engine performance.