P006B
MAP - Exhaust Pressure Correlation.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 0
- AreaFuel and air metering, auxiliary emission controls
- 6B
- FaultThe specific fault in that area
What it means
P006B is a generic code meaning the control unit has found that the manifold absolute pressure (MAP) reading does not correlate with the exhaust pressure reading. The two pressures are compared against each other, and against what is expected for the current load and boost, and the code sets when the difference is outside the allowed range. It is mostly seen on turbocharged diesel and some petrol engines that fit an exhaust pressure sensor, and the exact strategy varies by model and engine.
Symptoms
- Engine warning light on, sometimes with other boost or EGR codes
- Loss of power or the car going into limp mode
- Poor or hesitant acceleration, especially under load
- Black or excess smoke from the exhaust
- Increased fuel consumption
- Particulate filter regeneration problems on diesels
Possible causes
- Faulty or contaminated MAP sensor or exhaust pressure sensor giving an inaccurate readinglikely
- Blocked, split or disconnected sensor pipes or hoses, including soot-clogged exhaust pressure sensor tubeslikely
- Exhaust restriction such as a blocked particulate filter or catalytic converterlikely
- Boost leak or intake leak affecting the manifold pressure readingpossible
- Turbocharger fault, such as a sticking variable geometry mechanism or wastegatepossible
- Wiring or connector damage, corrosion or poor earth/supply on either sensor circuitpossible
- Control unit fault or outdated softwarerare
How to diagnose
- Read all stored and pending codes and the freeze frame data, noting load, engine speed and boost at the time the fault set
- Inspect both sensors, their connectors and wiring for damage, corrosion, heat damage or loose pins
- Check the pipes or hoses to the exhaust pressure sensor for blockages, cracks or leaks, and look for soot build-up
- Inspect the intake system, intercooler and hoses for splits, loose clamps and oil leakage that could cause a boost leak
- Compare live MAP and exhaust pressure readings at key off, then at idle and under load, against specification for the engine
- Check sensor supply voltage, signal and earth with a multimeter against the manufacturer data
- Check particulate filter or catalyst condition, such as differential pressure readings and soot load, and look for an exhaust restriction
- Test turbocharger actuator and boost control operation, following the model-specific procedure
How to fix
- Replace the faulty MAP or exhaust pressure sensor once testing confirms it is at fault
- Clear or replace blocked, split or perished sensor pipes and refit them correctly
- Repair wiring or connector faults and restore proper supply, signal and earth
- Repair boost or intake leaks by replacing damaged hoses, clamps or intercooler parts
- Rectify an exhaust restriction by repairing or replacing the particulate filter or catalytic converter as required, after finding the underlying cause
- Repair or replace the turbocharger or its actuator if testing shows a fault, and apply a software update only if the manufacturer lists one for this fault
Can I keep driving?
The car can usually be driven carefully for a short time, but power may be limited and an exhaust restriction or turbo fault can get worse. Have it diagnosed soon, and stop if power drops sharply, there is heavy smoke or other warnings appear.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.