VW T6 CXEB flashing glow plug light, no fault codes: a diagnostic pathway to low oil pressure

The Problem

A 2017 VW T6 204 DSG (CXEB engine) developed a flashing glow plug warning light within the first 90 seconds of driving, with no fault codes showing on a generic OBD2 scanner and the fault clearing itself on restart. The owner had already spent money replacing the oil pressure sensor, glow plugs, and an injector without resolving the issue.

Solution

1. Upgrade your diagnostic tool before replacing any more parts — a generic OBD2 scanner will not read fault code P164B00 on the CXEB engine and will falsely report no faults.

   • Use VCDS (Ross-Tech) or a professional workshop scanner such as Snap-on to retrieve codes accurately.

2. Retrieve the stored fault code; on this engine it will likely come back as P164B00, indicating a low oil pressure sensor malfunction.

   • This code can be a red herring — it may reflect a genuine low pressure event caused by mechanical wear rather than a faulty sensor.

3. Perform a mechanical oil pressure gauge test early in the diagnostic process to confirm whether actual oil pressure is low or whether it is a sensor or wiring fault.

   • Skipping this step early on is a costly mistake — do the mechanical test before condemning any parts.

4. Run live data on the oil pressure sensors and regulating valve using VCDS or a professional scanner to observe real-time sensor behaviour before condemning any components.

5. Send an oil sample for analysis to check for fuel dilution, which is a known issue on the CXEB engine.

   • 2% fuel dilution is the caution threshold; 4% is the alert level, and sub-standard lubrication can trigger low pressure events on this engine.

6. If live data and the mechanical pressure test suggest a sensor fault, replace the low oil pressure sensor (the green sensor at the top rear of the engine) with a genuine VW part rather than an aftermarket alternative.

   • OEM part number: (verify part number before ordering with your VIN at a VW dealer parts desk, as sensor specifications vary across the 2.0 BiTDI build period).

7. If the fault persists, replace the high oil pressure sensor (brown sensor) and the oil pressure regulating valve with genuine parts, and perform an oil and filter change using a 5W-30 long-life specification oil.

   • OEM part numbers for the high-pressure sensor and the oil pressure regulating valve: (verify part numbers before ordering against your VIN, as these differ between engine variants).

8. If the fault still persists after all sensors and valves have been replaced, consider replacing the oil pump and cleaning the sump.

   • The CXEB 2.0 BiTDI uses a chain-driven, variable-output (regulated) oil pump rather than a simple fixed-displacement unit, so confirm the correct pump variant against your VIN before ordering — give the parts desk your VIN, as the regulated pump assembly is not interchangeable with the single-stage pump used on lower-output 2.0 TDI engines. (Verify part number before ordering.)
   • This is a significant job: the sump must be dropped to access the pump, and on a 4MOTION van the subframe and driveshaft clearances make this more involved. Expect a substantial labour bill — typically in the region of 6–10 hours at an independent specialist, and longer at a main dealer. Because the sump has to come off anyway, clean it thoroughly and inspect for debris or bearing material while you are in there, as metal in the sump points back to the wear diagnosis in step 9.

9. If the fault continues after all of the above and oil consumption is around 1 litre per 2,000 miles with no visible leaks or exhaust smoke, the likely root cause is internal engine wear — worn bores or bearing surfaces causing genuinely low oil pressure at high rpm.

   • This is consistent with the known reliability threshold of the CXEB 204hp twin-turbo engine around 100,000 miles, and is supported by the fault only triggering above approximately 3,500 rpm once oil reaches operating temperature.
   • At this point the diagnostic pathway has run its course: the realistic options are an engine rebuild or replacement, so weigh the cost against the value of the van before committing to further parts.