P050E
Cold Start Engine Exhaust Temperature Too LowP050E is a generic OBD-II powertrain diagnostic trouble code: Cold Start Engine Exhaust Temperature Too Low. It is logged by the engine control unit when the glow monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P050E means
P050E is an SAE generic powertrain code set when the engine control module (ECM) detects that exhaust gas temperature during a cold-start event is below the expected threshold. On diesel engines equipped with diesel particulate filters (DPF) or selective catalytic reduction (SCR) systems, the ECM monitors exhaust temperature from start-up to ensure the after-treatment system reaches operating temperature within a defined time window. If the measured temperature remains too low for too long, the monitor trips and the MIL illuminates.
The most common root causes on modern diesel applications are a failed or lazy exhaust gas temperature sensor, restricted or blocked glow plugs that prevent the combustion chamber from reaching normal cold-start temperature, or faults in the glow plug control module. An EGR valve stuck open can also route cold recirculated gas back into the manifold, suppressing exhaust temperature during warm-up. On some turbocharged applications, a large exhaust leak upstream of the sensor will cause under-reading.
Because this code is directly linked to after-treatment warm-up, the ECM may extend post-injection or increase idle speed to compensate, leading to elevated fuel consumption on affected trips. Repeated cold starts without resolution can cause DPF under-regeneration, progressively shortening DPF service life. Diagnosis should begin with live EGT sensor data during a cold start, followed by glow plug resistance tests and EGR valve position checks.
Common causes
Most-frequently reported root causes when P050E is logged.
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1
Faulty exhaust gas temperature (EGT) sensor — sensor drifted low or open-circuit
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2
Failed or low-resistance glow plug(s) preventing adequate combustion heat
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3
Defective glow plug control module not energising glow plugs
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4
EGR valve stuck open, cooling the exhaust stream during warm-up
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5
Exhaust leak upstream of the EGT sensor diluting measured temperature
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6
Damaged or corroded EGT sensor wiring or connector
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7
Low compression reducing combustion efficiency and exhaust heat output
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8
ECM software fault or miscalibrated cold-start temperature model
Symptoms drivers notice
How to diagnose P050E
A typical diagnostic flow when this code is present.
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1
Connect a scan tool and record live EGT sensor data during a cold start; compare against ambient temperature and expected rise curve
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2
Inspect EGT sensor connector and wiring for corrosion, chafing, or pin-back — repair or replace as needed
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3
Test EGT sensor resistance/voltage against manufacturer specification at known temperature; replace if out of range
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4
Test each glow plug for correct resistance (typically 0.5–2 Ω) and verify glow plug relay/control module output voltage during cranking
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5
Check EGR valve operation with a scan tool — command it closed and confirm exhaust temperature rises normally during warm-up
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6
Inspect for exhaust leaks at manifold gaskets and downpipe joints upstream of the EGT sensor
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7
Perform a compression test if glow plugs and sensors are satisfactory, to rule out low-compression cylinder(s)
Vehicles where we've handled P050E
Platforms in our catalogue with confirmed P050E coverage.
Related powertrain codes
Frequently asked questions
Can P050E be triggered by cold weather alone?
Extremely cold ambient temperatures can stress the system but a correctly functioning glow plug system and EGT sensor should still keep the ECM within its expected model. If the code appears only below −15 °C and glow plugs test good, check for a slow-response EGT sensor before condemning other components.
Will P050E cause limp mode?
On most applications this code sets the MIL without immediately triggering a limp-mode torque reduction. However, if left unresolved it can trigger secondary DPF or SCR-related faults that do invoke limp mode, so prompt diagnosis is recommended.
How does P050E differ from P050D (Cold Start Rough Idle)?
P050D monitors combustion smoothness at idle during cold start; P050E specifically monitors exhaust temperature as a proxy for after-treatment warm-up adequacy. Both can be caused by glow plug faults, but P050E is more directly linked to EGT sensor readings and after-treatment system performance.
Is it safe to drive with P050E active?
The vehicle is generally drivable, but continued driving without repair accelerates DPF soot loading because regenerations may not complete. On vehicles with SCR systems, NOx conversion efficiency will also be reduced. Repair within a few hundred kilometres is advisable.
Disabling P050E in software
RaceTune can permanently disable P050E — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
ECUs with a P050E disable in our catalogue
Confirmed coverage from our recipe database — we support many more families. Upload your file and our identifier will match it automatically.
- Bosch EDC17C74 verified 1 software version
- Bosch EDC17CP44 verified 1 software version
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
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