OBD-II Code

P1402

Severity

Not yet reviewed

Nobody on our side has assessed this code yet, so we are not going to guess at how serious it is.

Can you drive it

We cannot say

Treat it as unknown until a shop reads it with live data. If the check-engine light is FLASHING, stop driving as soon as it is safe to — that means an active misfire, whatever the code.

Indicative cost (USD)

$150–$2,800

From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.

$150 (clean and reinstall existing valve) to $2,800 (new EGR valve, new EGR cooler, intake manifold walnut blast, all gaskets).

How a shop works this

Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.

Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then follow the diagnostic notes further down this page, in the order they are written.
They are written in the order a shop works this code, cheapest checks first. Where they name a component, inspect its wiring and connector before replacing it.

If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.

Common symptoms

Check engine light

Read the full diagnostic procedureP1402 on a Mercedes with the M642 3.0L OM642 BlueTec diesel (E320 BlueTec, E350 BlueTec, ML320/ML350 BlueTec, GL320, Sprinter) is an EGR Valve Positi…+

P1402 on a Mercedes with the M642 3.0L OM642 BlueTec diesel (E320 BlueTec, E350 BlueTec, ML320/ML350 BlueTec, GL320, Sprinter) is an EGR Valve Position Sensor fault — the EGR valve is an electrically-actuated butterfly with an integrated position-feedback sensor, and the ECU compares commanded position (0-100% open) against the sensor's actual reading. The position sensor outputs a 0-4.5V signal that scales to 0-100% open; healthy operation shows ~0.5V at fully closed and ~4.2V at fully open, with the ECU expecting the sensor reading to track commanded position within ±5% during operation. P1402 sets when the sensor signal stays stuck, reads outside the 0.3-4.7V plausible range, or fails to respond to commanded movement within ~500ms.

Diagnostic order

Scan live data — watch "EGR Position Commanded" versus "EGR Position Actual" through an idle-to-2000-RPM sweep; if commanded climbs to 60% and actual stays at 5%, the valve is mechanically seized with soot (extremely common on OM642 at 80-120K mi).
Pull the EGR valve, inspect for the carbon brick that always accumulates on the butterfly shaft — most OM642 EGR valves can be cleaned with carb cleaner and a brass brush, then reinstalled with a new gasket for $25.
If cleaned valve still throws the code, the integrated position sensor is bad and the valve must be replaced as a unit (Mercedes doesn't sell the sensor separately on this generation). Expensive-misdiagnosis caveat: don't replace the EGR valve before checking the EGR cooler and intake manifold for catastrophic soot loading — on the OM642, a clogged EGR cooler creates backpressure that physically prevents the valve from reaching commanded position, and a brand-new $700 EGR valve will throw P1402 again within 200 miles if the cooler and intake aren't walnut-blasted or replaced at the same time. The full "EGR delete and intake clean" job on an OM642 runs 6-8 shop hours.

Vehicle-specific patterns2007-2009 Mercedes E320 BlueTec (W211) and 2010-2012 E350 BlueTec (W212) with the OM642 are the canonical P1402 vehicles — soot accumulation in the E…+

2007-2009Mercedes E320 BlueTec (W211) and 2010-2012 E350 BlueTec (W212) with the OM642 are the canonical P1402 vehicles — soot accumulation in the EGR cooler and intake manifold is so consistent at the 100K-mile mark that the repair has its own labor-time entry at every diesel-spec independent shop.
2007-2012Mercedes ML320 BlueTec / ML350 BlueTec / GL320 BlueTec / R320 BlueTec with the same OM642 throws identical patterns, with added soot loading in cold-climate markets where short-trip driving prevents regen cycles.
2007-2018Sprinter vans with the OM642 (2500/3500 series) see P1402 even more aggressively because delivery-route stop-and-go usage prevents DPF regens — fleet operators replace EGR valves on a 60-80K mile preventive schedule. The closely-related M272/M273 gasoline V6/V8 platforms (W203/W204/W211/W212/W221, 2005-2014) don't use this code the same way — their EGR strategy is internal via cam timing, and their famous failure mode is balance-shaft gear wear setting P0016/P0017.

Estimated repair$150 (clean and reinstall existing valve) to $2,800 (new EGR valve, new EGR cooler, intake manifold walnut blast, all gaskets).

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