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Discussion Starter · #1 ·
Hello Guys,

This is regarding my Hyundai Matrix (Hyundai Lavita) car manufactured in 2001.

I drove the car in somewhere and parked. When I again start again the engine suddenly it was noticed unusual high rpm at starts (apx. 2500-3000 rpm).
There was no any check engine light shown in dash. I drove the car but it was noticed no need to press the gas pedal/accelerator even 2nd, 3rd gears (this is manual transmission car).
After drove about 3-5Km, I turned off the engine & pop the hood and I observed the oxygen sensor area in red hot condition (refer below). But heat level shows as usual in the dash. After few minutes cooling I check coolant levels and it was in good condition & desired level. Again, I start the engine & that issue disappeared and engine run as usual in good condition with desired rpm level (below 1000rpm).

I check this issue local mechanics and no one give clear explanation for the issue. Then scan the car computer following codes shown P1505, P0121 and P1507 (refer below). They advised to replace throttle position sensor. After clearing the codes & no any codes were shown in re-scan.

Is it worth to replace the “throttle position sensor”? what is the real cause as per your perspectives.

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I need your valuable comments.

· Super Moderator
2000 model Hyundai Lantra GLS 2.0 (G4GF) factory 5 speed manual. Fully optioned. Most things work...
148 Posts
The codes and the engine behavior are pointing towards a bad throttle position sensor. IMO if the TPS is faulty, it will try to run open throttle with the throttle butterfly closed and this will result in a very lean run. The IAC will then open in an attempt to supply extra air to the intake (this would explain the red hot exhaust) Anyone else reading your post might be able to add their input. Intermittent faults are hard to diagnose. Be warned that running the engine lean enough to get the exhaust manifold glowing may result in the manifold cracking.
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