Can a dodgy exhaust temp sensor cause this issue in a Hyundai Tucson?
The question
Hi,
I’m looking for some advice on a 2019 Hyundai Tucson 1.6 CRDi automatic, with 123,000km on the clock.
On the drive home from the dealer I bought it from I noticed intermittent power loss/surging, mainly at speeds over 100 km/h. It gives 3–5 quick surges where the power briefly drops and comes back, then can drive normally for 10–15 minutes before happening again.
The engine light came on initially. I returned it to the dealer and they carried out a DPF regeneration, saying the DPF was the problem. The car drove normally for about four days, then the exact same fault returned.
The original diagnostic scan showed:
P20EE00 – SCR NOx catalyst efficiency below threshold
P2BA800 – NOx exceedance/interruption of reagent dosing activity
P20C900 – reductant control module requested MIL
P24AE00 – particulate matter sensor circuit
P067100 – cylinder 1 glow plug circuit
B121100 – front centre-left sensor fault
The scan also showed estimated soot in the particulate filter of 18.98g.
The dealer has now carried out a Hyundai diagnostic and road test. Their report says they reproduced the fault at 120km/h using a flight recorder and “captured the fault on the current data.” They have diagnosed “EXH temp sensor 0 faulty” and say there are currently no active fault codes.
My question is: does an exhaust temperature sensor fault potentially explain the original symptoms and the codes above or should the DPF/SCR system be investigated further?
I'm within the first 30 days of purchase, so I need to decide very shortly whether to accept the proposed repair or reject the car. I don't want to replace a DPF unnecessarily, but I also don't want to accept a sensor repair if it doesn't address the underlying problem.
Any advice?
Asked by Jim Bolget ·
Expert answer
Hi Jim,
A faulty exhaust temperature sensor can certainly have wide-reaching effects on how an engine runs and may cause other issues as indicated by all those faults. What you’ve shown us does not necessarily indicate that the DPF is blocked or needs replacement.
Only you can make the decision on what to do with the car, but if this were my car, I’d be happy with the diagnosis and repair carried out as described. The one thing I would ask for is a restart of the warranty from the dealer on the car and work done, so that if any other issue arises, they will promptly sort it out.
Do let us know how you get on
Answered by Shane O' Donoghue